Original subtitles

NARRATOR: Vast, man-made caves

that defy explanation,

subterranean chambers

rumored to house profound knowledge

and enduring tales of an extraordinary civilization

concealed within the Earth.

For nearly two decades,

Ancient Aliens has traveled the globe

exploring towering megalithic structures,

mysterious artifacts

and stories of otherworldly beings

in a quest for evidence

that might reveal the truth of our extraterrestrial origins.

Our ancestors have always said,

"As above, so below."

NARRATOR: Now we take a look back

through the Ancient Aliens archives,

to the show's very origins,

to examine the evidence that we are not alone.

We have never been alone.

♪ ♪

We live on a truly fascinating planet.

I mean, anywhere you go,

you find ancient sites and artifacts,

some of which are still very mysterious to this day.

But what really blows my mind is how much of it

is still hidden underground.

And we're finding more all the time.

Like massive underground tunnels

and entire subterranean cities.

There's even a tomb in China that had rivers of mercury.

-Right. -WILLIAM HENRY: Oh, yeah, it's incredible

what they've found underground in China.

And I'm really glad we're starting this episode

with a story Ancient Aliens covered in 2015,

where these Chinese archaeologists discovered

a labyrinth of these man-made caverns

-that just totally defy explanation. -Yeah.

NARRATOR: Zhejiang province, China,

June 1992.

A local villager pumping water

out of a pond in Phoenix Hill uncovers

a man-made cavern with stairs,

hallways

and massive ten-story-tall pillars.

The grotto is one in a series of 24 separate caverns,

each with similar proportions

and intricately carved walls, floors and ceilings.

PAUL BAHN: Nobody really knows what on Earth these things are.

There's no trace of them having been occupied

or being used for storage.

Uh, certainly not for burials,

there's no trace of anything like that.

GIORGIO A. TSOUKALOS: There's a Swiss author

by the name of Luc Bürgin

who was first to take this story outside of China

in his book China's Mysterious Cave Labyrinth,

and what he showed me convinced me that some kind

of advanced technology was used here.

It's one of the most amazing things I've ever seen,

where you enter this subterranean world

that clearly has been hewn out of the bedrock

with artificial means.

It's almost as if there was some sort of artificial mechanism

that was grinding and drilling all of the stone out,

and this suggests the possibility

that they may have had some sort of technology.

NARRATOR: Archaeologists estimate

that the material excavated from the site

would amount to nearly one million cubic meters,

approximately the volume of 400 Olympic-sized pools.

Yet, there is no evidence

of where this material would have gone,

and Chinese officials have calculated

that an endeavor of this magnitude

would take a minimum of 1,000 men

working day and night for at least five years.

There is no historical record,

uh, of these caverns having been excavated,

so there's no document explaining

what they were used for, who excavated them.

And this remains a very, very, uh, frustrating detail

for historians.

ANDREW COLLINS: We know that, in China,

there are written records

that go back at least 3,000 years.

They make absolutely no mention of these caves.

So we must look much further back in time

for their origin.

But exactly how old are they?

Are they 4,000 years, 5,000 years?

Are they even 10,000 years?

We just don't know at this time.

TSOUKALOS: Some have suggested

that they're up to 15,000 years old.

In fact, Chinese scholars are the ones who have proposed

that this cave system dates back

to one of China's first emperors, Huangdi,

and Huangdi, as we all know,

descended from the sky in nothing else

but a fiery dragon.

DAVID WILCOCK: Somebody went to an extreme amount of trouble

to build an underground civilization.

Why would they do that?

Is it possible that something was happening

on the surface of the Earth?

When we go back to the Icelandic legends,

we see this cataclysm

that is described as a cataclysm of fire

called the Ragnarok,

in which you have flames in the air

and rocks and gravel raining down from the sky.

NARRATOR: In the Icelandic Ragnarok legend,

the world is turned upside down.

A great fire is followed by

a submersion of the world in water,

resulting in the death of the Nordic gods

and their offspring.

Only two humans are left to repopulate the Earth.

It is a tale much like that

of the great flood found in the Judeo-Christian Bible.

And similar stories of a great deluge,

one that marks the end of an old world

and the start of a new one, can be found in the histories

of virtually every ancient civilization on our planet.

ROBERT SCHOCH: Virtually every culture-- every ancient culture--

talks about floods and ancient floods.

Some people dismiss this as, you know, myth,

without explanation.

But what we find geologically

is, in fact, we would expect flood legends.

NARRATOR: In 2007,

a consortium of geologists

publishes its collective findings

indicating evidence of a major meteor event.

What they discover is a carbon-rich layer

in the geological record

at various sites across the globe,

dating back to around 10,900 BC.

A separate study conducted by scientists

studying Arctic ice core samples

finds evidence suggesting a rapid glacial melt

at nearly the same time period.

SCHOCH: The Ice Age ends very,

very dramatically, almost literally overnight.

You see this in the ice cores.

All of a sudden, there are dramatic changes.

Temperatures rising...

...torrential rains,

flooding.

NARRATOR: Could the geological record suggest

that the stories of a global cataclysm are true?

If so, might the stories of a cleansing

of the Earth of otherworldly beings,

leaving only humans to repopulate the planet,

also be true?

Ancient astronaut theorists say yes

and suggest further evidence may be found

by exploring another mysterious underground city

located nearly 300 feet beneath the earth.

You can't have a conversation about underground structures

without mentioning Derinkuyu in Turkey.

It's got to be one of the most incredible places

-on this Earth. -CHILDRESS: Yeah, Derinkuyu

is an entire city deep underground.

And it's anyone's guess how old it is,

but it goes back at least 3,000 years.

Oh, and we've proposed it's even older than that

because it's only about 300 miles from Göbekli Tepe,

and there, we know it dates back 12,000 years.

We covered that place in season two of Ancient Aliens,

and it's one of those sites that just blows you away.

Absolutely.

NARRATOR: Bordered on the north by the Black Sea

and by the Taurus Mountains to the south,

lies Cappadocia in Central Turkey.

Here, wind and water

have sculpted strange shapes out of the soft volcanic rock,

rock which ancient peoples

once turned into small, primitive dwellings.

In more recent years, the site has seen

the construction of more modern structures.

But in 1963,

a simple home renovation in the town of Derinkuyu

led to an extraordinary discovery

when a cave wall was opened,

revealing a passageway to an underground city

thousands of years old

and more than 280 feet deep.

TSOUKALOS: I've been there on multiple occasions,

and it's incredible because there's 13 stories

that go deep into the ground,

with ventilation shafts and 15,000 little shafts

that bring air to even the deepest of levels.

NARRATOR: Incredibly, the number of rock rooms that were found

could hold over 20,000 men, women and children.

There was even evidence of religious centers,

storerooms,

winepresses

and stables for livestock.

JOHN BRANDENBURG: Oh, Derinkuyu

would've been a massive undertaking for anyone,

even in modern times with modern equipment.

But in those days, it would've been, um, stupendous.

Equal to the pyramids.

At Derinkuyu, because of the softness of the stone,

you had to be very careful that you provided

enough pillar strength to support the floors above.

Otherwise, you'd have catastrophic cave-ins.

Surprisingly, there's no evidence

of any catastrophic cave-ins,

so they were apparently extremely clever

and knew their material.

We're talking deep antiquity.

It is mind-boggling

to understand how they could've done this.

Perhaps they had help from some other civilization.

NARRATOR: But just who built

this massive underground city?

And what mysterious force drove them

to live underground?

CHILDRESS: Why would people want to live deep underground

in these weird caverns like that?

It seems kind of scary, really.

NARRATOR: According to many archaeologists and scholars,

Derinkuyu was most likely intended

to serve as a temporary shelter from invasion,

built around 800 BC by the Phrygians,

a Bronze Age people related to the Trojans.

Others believe it was built by the Hittites,

a warrior people mentioned in the Bible

who flourished hundreds of years earlier.

But could the underground city be even older?

According to ancient astronaut theorists, it is,

perhaps by many thousands of years.

WILCOCK: The Cappadocia region of Turkey was part

of the Zoroastrian Empire, which was Persian in nature.

And it's one of the oldest religious traditions

on the face of the Earth.

NARRATOR: The Zoroastrian religion,

an ancient faith

based on opposing forces of good and evil,

is widely believed to have influenced both Hinduism

and Judeo-Christianity.

Founded sometime before the sixth century BC,

its chief god is the creator Ahura Mazda.

And in the second chapter of the Zoroastrian sacred text,

the Vendidad,

Ahura Mazda saves mankind

from a worldwide environmental disaster,

much like the story of Noah in the Hebrew Testament.

TSOUKALOS: The great prophet Yima, he was instructed

to build a kind of underground refuge

similar to Derinkuyu by the sky god, Ahura Mazda.

NARRATOR: According to the sacred texts,

Yima built a multi-level underground city

to protect a select group of people and animals

not from a flood but from a global ice age.

The Vendidad calls this "the evil winters."

According to many mainstream climatologists,

the last ice age peaked around 18,000 years ago

and ended around 10,000 BC.

Is it possible that Derinkuyu was built as a refuge

from a devastating global winter?

TSOUKALOS: Since you cannot carbon-date stone,

it's anybody's guess how old Derinkuyu really is.

And my question is,

if we have a Zoroastrian story that's very similar,

could it be that both that place

and Derinkuyu are much, much older

than what we've believed so far?

NARRATOR: But if Derinkuyu is, in fact,

the underground city that Ahura Mazda

told his followers to build,

could there be a stunning truth behind the legend?

If so, who or what

was the god Ahura Mazda?

WILCOCK: Ahura Mazda does appear to be

responsible for the management

of whatever is happening here on Earth.

There are various ways to read this,

one of which is that it does represent some sort

of higher universal form of consciousness.

But another is that it would represent

an overseeing extraterrestrial intelligence.

JASON MARTELL: Several sacred texts

from antiquity speak of knowledge given to mankind

from extraterrestrials, but also known as gods from antiquity.

NARRATOR: Could the sky god Ahura Mazda

really have been an advanced being from another world?

If so, did he provide the technology needed

for his followers to build this complex labyrinth

as protection from environmental disaster?

Or is there possibly a more ominous reason

for Derinkuyu's existence?

Some say a clue lies

in the underground city's unusual security system:

1,000-pound doors on rollers

that allow them to be moved by a single person

but only from one side.

The Derinkuyu doors, they're very cleverly constructed.

You can basically only open it and leverage it from the inside.

TSOUKALOS: So, obviously, whoever inhabited Derinkuyu

was hiding from someone or something.

NARRATOR: According to the ancient Zoroastrian texts,

Ahura Mazda soared through the sky in a divine chariot

and waged war against his eternal enemy,

Angra Mainyu, the Demon of Destruction.

But could this really be,

as many ancient astronaut theorists believe,

a depiction of two extraterrestrial forces

battling over control of the Earth and its resources?

The aerial enemies were extraterrestrials,

because they were the ones who had the capability of flight.

They had access to those types of machines

that we can read about

in every single ancient culture around the world.

WILCOCK: When you look at the Zoroastrian tradition,

you also see clear evidence that there was

some sort of extraterrestrial battle going on

between warring factions.

Therefore, it is certainly possible

that the original caves may have been used as shelters

against possible aerial bombardment

from extraterrestrials that were warring

with each other during that time.

Derinkuyu was built out of fear of an aerial enemy,

because if something flies over you very, very fast,

you can't see the ventilation shafts.

Some suggest 30,000 people

used to live underground at Derinkuyu.

NARRATOR: During recorded history, many different peoples did,

in fact, hide in the underground city

of Derinkuyu to escape everything

from desert raiders to Roman legions.

But some experts wonder whether such conventional attacks

can really explain why Derinkuyu was built in the first place.

TSOUKALOS: If it were an enemy that was on horseback,

it would be easy for them to just smother everyone inside

by just closing all the ventilation shafts.

BRANDENBURG: We had the phrase in the Defense Department studies

that I participated in that "a cave is a grave

to a well-prepared adversary."

Once you find it, it is highly vulnerable.

NARRATOR: But did the people of Derinkuyu really go underground

to avoid becoming casualties

in an extraterrestrial battle in the skies?

And if so, might there be

other such cities from the distant past?

According to ancient astronaut theorists, there are,

and they can be found much nearer to home,

deep in the caves of the American Southwest.

NARRATOR: The majestic mesas and rugged mountains

of the American Southwest

are home to many Native peoples,

including the Navajo,

Zuni,

Pueblo, Hopi

and Apache.

These tribes have many different beliefs,

but their creation myths all share

something quite remarkable.

JAY VIGIL: When we talk about our origin,

and, you know, you hear the stories about us coming down

from Alaska through the Bering Strait,

but what we believe is we came up from the ground.

CHILDRESS: The Apaches and other Pueblo Indians,

such as the Zunis and the Hopi Indians,

all have this legend that they

emerged from some underground world

into today's world.

NARRATOR: In some legends, the Southwestern peoples

went back underground for safety.

(tribal chanting)

The Hopi of Arizona say their ancestors escaped

a deadly storm of falling stars...

...with the help of the Snake People,

who took them to shelters deep in the Earth.

Another Hopi legend speaks of the Ant People,

who protected them from storms of fire and ice.

CHILDRESS: The Hopi Indians survived cataclysms

by living in this underground world

with the Ant People for a certain period of time,

and then eventually they emerged from the underground world

back into the surface world.

NARRATOR: Ant People.

Snake People.

Could these stories be based on ancestral tales

of people actually living underground,

possibly during the last ice age?

Or could the ancestors of today's Southwestern tribes

have taken refuge in subsurface dwellings

similar to the underground city of Derinkuyu in Turkey?

If so, over the centuries,

might they have developed physical traits,

like large eyes and fingers,

that made them more closely resemble

actual Earth-dwelling creatures?

The shamans and the elders of Native Americans,

they will tell you that before

these people were able to emerge out of planet Earth,

they were brought here by the star people,

the star gods, which arrived from outer space.

LINDA MOULTON HOWE: I have stood in front of

what are called the Ant People

and some of the very strange,

large-eyed drawings on the rocks

and wondered, "Am I looking

"at Native American interpretation

"of what today is called

an extraterrestrial biological entity?"

TSOUKALOS: If extraterrestrials were here in the remote past,

there are multiple species out there,

is it possible that they might have looked

lizard-like and ant-like?

And the answer is yes.

NARRATOR: Is it possible that these underground creatures

of Native American legend were actually alien visitors?

If so, could some of them still be living

beneath the surface of the Southwestern desert?

For decades, stories of encounters

with UFOs and alien beings

have been told among the people

of New Mexico's Jicarilla Apache Reservation.

Some of the aliens in these stories bear

a strange resemblance

to the ancient tales of the ant-like

and snake-like beings from the Hopi legends.

There is things up here that no one can explain.

NARRATOR: The Jicarilla Apache Reservation is located

next to the small town of Dulce,

nestled in the shadow

of the over-9,000-foot-high Archuleta Mesa.

It is from this mesa and mountain

that people claim they have seen UFOs

flying out of the mountain.

It was a spaceship we saw right there.

And it was big.

Like, maybe the size of a football field.

And then we seen this dome on top that was all glassed in.

And then my husband was looking at it

with the binoculars, and he saw two small people.

Well, we don't know what it is.

If we stayed here and they came down,

I don't know what they would have done to us.

♪ ♪

NARRATOR: Could the Native tales of spaceships

and strange creatures be true?

Some UFO researchers and conspiracy theorists

believe that these eyewitness accounts are

not only true but are evidence of a secret collaboration

between underground aliens and the U.S. military.

The amount of military traffic over Dulce,

the unmarked helicopters, the black helicopters,

the heavy-duty Chinooks,

all these helicopters spend

a lot more time in Dulce than they should

if nothing were going on here.

Among the stories that we've heard

from the Jicarilla Apache is that

they discovered vents actually right here on the mesa.

JAY VIGIL: A while back, uh,

when my brother was still alive, we used to come up here

in the back, and he showed us this shaft,

and that thing was bigger than... bigger than me.

But we walked in, and I didn't want to go any further.

BILL BIRNES: The vents were here maybe 25 years ago.

You'd hear strange noises.

Groans.

Sighs.

Human groans.

And this led a lot of credence

to stories that human beings were

being vivisected, experimented on.

And thus the legend of strange creatures

and strange noises coming out of this mesa

grew and expanded.

NARRATOR: Aliens living underground?

Strange, secret government cover-ups?

Could Native American legends of underground beings

help unearth the truth behind these incredible stories?

Perhaps additional clues can be found

by analyzing ancient cave art

depicting curious humanoid figures.

In almost every ancient culture,

there are stories of beings coming down from the sky,

but there are also stories of beings living beneath the earth.

-Right. -HENRY: There really are.

In the Native American tradition,

we learn about the Snake People, the Ant People.

Then there's this cave art

that shows these humanoid figures

with these really strange-looking bodies.

Yeah, and some of these figures that you're talking about

can be found in the Grand Canyon.

In fact, we covered them

in a 2014 episode of Ancient Aliens

called "Forbidden Caves."

NARRATOR: Santa Monica, California.

2014.

Here at xRez Studio,

visualization artists Greg Downing

and Eric Hanson are pioneering the use

of photogrammetry and special effects software

to assist archaeologists in the global effort to decipher

ancient cave art.

GREG DOWNING: We use a combination of techniques

from the fields of computational photography and graphics,

uh, in order to help the archaeologists

reveal information difficult to see

just with basic vision when you're there.

NARRATOR: The team recently traveled

to the Grand Canyon to compile a massive,

in-depth photographic compilation

of the collection of strange petroglyphs

known as the Shaman's Panel.

We were drawn to the panel for two primary aspects:

One was the rich layering

of the, uh, anthropomorphic figures,

and two is the kind of evocative,

uh, surreal nature of their composition.

DOWNING: This cave is maybe, like, five or six feet deep.

So by using a photogrammetric technique,

we're able to get the detail across the entire painting.

HANSON: The nice thing about this technique is

we can separate the different dyes

and minerals that are used.

And in this case, now we can kind of see

the layering expressed.

We can see figures that are simply lost by the naked eye.

Yeah, that brings it out.

DOWNING: Yeah, that's a complete difference.

NARRATOR: Could modern techniques one day uncover

even more details

about what ancient people really saw

and hoped to communicate with rock art?

Some ancient astronaut theorists believe

one compelling clue that modern researchers

might be on the right track

can be found, oddly enough, in contemporary America.

March 1945.

Amazing Stories magazine publishes an article

entitled "I Remember Lemuria."

But according to the author,

this is the first piece to appear

in the science-fiction magazine that is not fiction at all

but an actual account of his own alien abduction.

REDFERN: Richard Shaver was a man

who surfaced decades ago with a story

of underground entities

that were very hostile to the human race.

Terrible creatures that would kidnap

and kill members of the human race.

TIM SWARTZ: They were the first inhabitants of planet Earth.

When the Sun became radioactive,

these people could no longer live on the surface.

Some left in their spaceships.

Others went underground.

NARRATOR: Could Richard Shaver's account

of underground extraterrestrials abducting humans be true?

Shaver proposed that the alien race

that once populated the Earth had developed

highly specialized equipment that allowed them

to embed multifaceted imagery into stones.

TUCKER: Richard Shaver believed

that he had made the greatest discovery

in the history of mankind

about the true nature of intelligent life on Earth.

So, this is an original Shaver photograph of a rock book.

And this multidimensional way of making images

in the rock books was something that Shaver saw as a real sign

of the superior intelligence of the ancient races.

And Shaver believed that these weren't mere rocks

with random patterns, that these were actually

deliberately manufactured artifacts by the ancient races

who had been here 30,000, 100,000,

who knows how many years ago.

NARRATOR: Might Richard Shaver have actually discovered

real physical evidence that extraterrestrials

have been here on planet Earth and might still be here today?

Whether or not Richard Shaver's stories are true,

it does dovetail with legends across this planet

of a race of beings that either created humankind

or were at least our ancestors

that had a superior technology.

REDFERN: If we're looking for extraterrestrials, ironically,

the heavens above might not be the best place to look.

We should, perhaps, even be looking deep below our feet.

CHILDRESS: In some ways,

exploring the underground cavern world

of planet Earth is-is the final frontier.

NARRATOR: Is it possible

that some of the world's most mysterious caves

really are home to extraterrestrial beings?

Could it be that the knowledge of the universe

has been left for us to discover right here on Earth

once we have the technology to unlock it?

Perhaps we will find proof by searching deep underground.

NARRATOR: Los Angeles, California.

January 1934.

The Los Angeles Times publishes

an article entitled "Lizard People's Catacomb City Hunted,"

accounting the attempt by mining engineer G. Warren Shufelt

to locate and excavate a maze of tunnels

which he believed were beneath the streets

of Downtown Los Angeles.

CREASON: Warren Shufelt was a mining engineer,

and he invented a device,

uh, that he called the radio X-ray,

to be used for gold mining,

and this device could find tunnels underground.

And he actually created a map of the tunnels.

NARRATOR: Included on Shufelt's map of tunnels

were 16 places where he said he had located gold deposits.

Shufelt gained momentum after meeting

with a Hopi medicine man who told him the legend

of the Lizard People that live in underground cities.

CREASON: Warren Shufelt had a sit-down

with an Indian medicine man in Arizona

who told him there was a Hopi legend

that there was three cities on the Pacific coast

that were completely underground.

The-the story goes that

5,000 years ago there was a meteor shower

and these Lizard People sought refuge underground.

They dug these tunnels,

and one of the network of tunnels

was under the city of Los Angeles.

NARRATOR: According to the legend,

the Lizard People carved out vast chambers

large enough to house a thousand families

using advanced technologies

such as a mysterious chemical

that could easily bore through bedrock.

Shufelt obtained permission from the city

and began digging to try and reach the vast tunnel system.

The city council, perhaps motivated

by the alleged gold that was contained within the tunnels,

allowed Shufelt to dig a 250-foot shaft

under the agreement that he would give them

50% of the treasure, if recovered.

CREASON: Warren Shufelt was a successful mining engineer,

and it seems that he had some kind of connection

at the Los Angeles Times,

'cause the Times really followed the story.

It was a story that caught the popular imagination.

NARRATOR: After a month of digging

and not reaching the tunnel system,

Warren Shufelt and his team ran out of money

and stopped the search.

But fascination with the story continues to this day.

So now we have these stories of-of underground people,

a race living underground in-in tunnels and bases.

And you have to wonder, is this some kind of

reptilian extraterrestrials

who have taken control of our planet

and are living underground?

It seems incredible, and yet,

it's what some of the stories are telling us.

NARRATOR: Is it possible

that an advanced race of Lizard People

once lived underneath the Western United States?

And could they still be there today?

Astonishingly, a nearly identical legend exists

halfway around the world.

Benares, India.

Within this city lies the Well of Sheshna...

...which in Hindu legend is an entrance

into an underground city of the nagas,

a race of semidivine serpent people

known throughout Eastern culture.

JONATHAN YOUNG: In Benares, the sacred city of India,

there is a well, the Well of Sheshna.

This is one of the portals

to the underground city called Patala,

and the nagas live in this place.

It's a place of great power and mystery and some danger,

and only the holy can make contact with it.

Patala is the underworld in Hindu mythology.

There are many beings that live in there,

many reptilians, which are called nagas.

As a demigod, they must have descended

from heaven to the Earth to teach,

to give special qualities, to the human world.

Nagas are not really evil,

being as in Judeo-Christian context.

NARRATOR: Ancient astronaut theorists claim the Hindu stories

of the nagas bear a striking resemblance

to the Hopi stories of Lizard People,

who also resided beneath the earth.

So here we are linking the naga, the serpent beings,

with the reptilian beings of the Hopi tradition.

We see a common thread here of these beings

who are, at one time, reviled and also revered,

but also as beings that have a direct influence on humanity.

NARRATOR: Is it merely coincidence that extremely similar legends

of advanced reptilian beings living underground

can be found on opposite sides of the world?

And is it possible these reptilian underground dwellers

surface every so often to interact with humanity?

Perhaps more clues can be found

in artifacts unearthed in the cradle of civilization.

Southern Iraq, 1923.

British archaeologist Sir Leonard Woolley

leads an excavation to uncover the remains

of one of the oldest agricultural communities

in the world, the Ubaid culture,

which dates back to 5900 BC.

Among the remains, they discover some unusual clay artifacts.

Among the dwellings and tools, they also discovered

these strange-looking clay figurines.

And I say "strange" because they don't really look human.

They have the facial features

of what seems to be reptiles.

Now, is it possible that the Sumerians

were depicting a race of beings

that were living among them at the time?

NARRATOR: Mainstream scholars have debated

the meaning of the statues since their discovery,

thinking perhaps they were Sumerian gods.

However, ancient astronaut theorists believe the statues

could have a different meaning.

These clay figurines have these

what are called coffee-bean eyes.

They have these elongated skulls.

They look very much like

some kind of reptilian extraterrestrial.

And they're breastfeeding children

and doing very normal human things

that you wouldn't think that gods would necessarily be doing.

So it's this mixture of human activity

with these reptilian aliens.

So we're showing mammalian reptilian physiology.

When it shows them, um, holding those babies,

it's not a normal thing to have anywhere

in iconography throughout the entire World.

And it makes you suspect to whether or not

they had actual physical contacts between them.

NARRATOR: Could it be that legends and artifacts

left behind by ancient societies

offer insight into a subterranean realm

and the beings that inhabit it,

a reality that has since been concealed from mankind?

According to ancient astronaut theorists,

the answer is a resounding yes,

and additional evidence could lie buried

deep beneath the Giza Plateau.

One of my favorite places on Earth is Egypt.

And what's crazy is that when you go there today,

you see the pyramids and temples and monuments on the surface,

but Egyptologists estimate that as much as two-thirds

of what the ancient Egyptians built

is still beneath the sands.

Yeah, and they're making more

discoveries like this almost every day.

And one of the most enduring mysteries

is what's underneath the Sphinx.

Yes, and the famous psychic Edgar Cayce

said that there was a secret chamber

beneath the Sphinx in the 1930s,

and new evidence shows that there is one.

Right.

And we covered this in season three

of Ancient Aliens.

NARRATOR: 1936. The Giza Plateau, Egypt.

For more than 3,000 years,

the body of the Great Sphinx

had been buried beneath the sand.

But after 11 years of work,

Egyptian archaeologists uncovered the entire monument

for the first time since antiquity.

At 241 feet long and 66 feet high,

it is the largest and oldest

monolithic statue in the world.

Even more incredible is its shape.

The Sphinx has the head of a man

and the body of a lion.

Although Egyptologists date the construction

of the Great Sphinx to the reign

of the Pharaoh Khafre in approximately 2500 BC...

...others claim its construction could be much, much older.

ROBERT BAUVAL: The orthodox dates

of about 2500 BC tagged on these monuments

has been challenged by a group of researchers,

including myself, who have argued

that the erosion of the Sphinx

suggests a much, much older Sphinx.

NARRATOR: Although Egyptologists have found no agreement

as to when or why this strange monument was built,

ancient astronaut theorists believe it may offer proof

of extraterrestrials being present in ancient Egypt.

MARTELL: We see in many ancient Sumerian

and Egyptian inscriptions of sphinxes,

half-man, uh, half-animal of some kind,

and a variance to a degree of different combinations

of animals and human beings.

We have to wonder, why would they be doing this?

And, logically, it starts to make more sense

when we realize a lot of these ancient texts

explain that extraterrestrials came here

and created us in their image and after their likeness.

GEORGE NOORY: If you believe the work of the late Zecharia Sitchin,

where he believes that the Anunnaki came from a planet

that is somewhere out in our solar system,

and that they came here to mine for gold.

But they figured, they're not gonna do the work themselves,

so they decided to take what creatures were on this planet

at the time, genetically alter them

and make mankind.

MARTELL: And if that's the case,

it's very possible that they could be using

genetic alterations to experiment

with not only just humanity

but a mixing of other species with humanity.

NARRATOR: Could the Great Sphinx be evidence

of genetic engineering by ancient aliens?

And if, as Zecharia Sitchin proposed,

extraterrestrials were genetically altering

humans and animals for the purpose of mining gold,

might this enormous structure

have at one point been a repository for that gold?

Is it possible that when Egyptian archaeologists

began excavating the Great Sphinx,

what they were really searching for was gold?

Over the centuries, secret chambers, shafts

and elaborate tunnel systems

have indeed been discovered all around the Giza Plateau.

BAUVAL: A shaft was discovered, called the Osirian Shaft,

which led under the Giza Plateau, behind the Sphinx.

Now, in that shaft are various passageways

that lead seemingly nowhere.

NARRATOR: In recent years,

ground-penetrating radar, or GPR scans,

have been conducted which reveal evidence

of numerous underground cavities

located not only around the Sphinx

but underneath it as well.

BAUVAL: From a scientific point of view--

I'm not talking about speculation and theories

and legends and so forth--

that was the very first time that some strong indication

that there might be these hidden tunnels

and chambers under the Sphinx.

And, according to this, they found very strong evidence

of what looked like artificial chambers.

COPPENS: And it's not a question as to whether or not,

uh, there is a secret underground passage

underneath the Giza Plateau.

The question is: Can we get access to this?

And, of course, the all-important question is:

Is there something there of extraordinary value,

maybe even something which defies science,

which might even be of an extraterrestrial nature?

NARRATOR: If the alleged cavities under the Sphinx

contain not only gold

but gold mined by ancient alien beings,

might they also contain something more

than just material treasure?

Ancient astronaut theorists believe

an elaborate secret repository

is located under the Sphinx's paws,

known as the Hall of Records.

It dates back to the fall of Atlantis,

which, according to ancient texts,

is said to have occurred nearly 12,000 years ago.

They also claim that there were extraterrestrials

living in Atlantis

and that they needed a repository

to house all of their accumulated knowledge.

ERICH VON DÄNIKEN: The Hall of Records,

it was made by us but with the tools

and the knowledge of extraterrestrials.

BAUVAL: It is speculated that

a group of survivors of Atlantis

came to Egypt at about 10,500 BC,

brought along with them their records,

their knowledge, and built this storeroom

somewhere at Giza.

NARRATOR: If archaeologists do someday

unearth secret chambers below the Sphinx,

what will they find?

Gold?

A library of ancient extraterrestrial knowledge?

Or perhaps something even more profound?

You know, ancient Egypt

isn't the only place that is rumored

-to have a hall of records. -Mm-hmm.

There are rumors that there are underground

repositories of knowledge all over the world.

And, in fact, I've been to one: Giorgio's basement.

(laughter)

Look, I live in California, David.

We don't have basements.

Okay, maybe Erich von Däniken's basement.

Well, he actually was one of the first ones

to write about this rumored hall of records in Ecuador,

and we covered this in season two of Ancient Aliens.

NARRATOR: South America.

The Andes mountain range in Ecuador.

For thousands of years, this rainforest,

high on the eastern slopes,

has been the land of the Shuar...

...headhunters who are fiercely protective of their homeland

and its secrets.

And of all the Shuar's secrets,

perhaps none has been so carefully guarded

as the location and entrance of the Cave of Tayos.

But why?

Perhaps the answer can be found in the story

of an Italian Catholic missionary named Father Crespi,

who lived in the region in the middle of the last century.

VON DÄNIKEN: Father Paolo Carlo Crespi.

He was loved by the Indians.

He helped them without, uh, asking for money.

And the Indians made him some presents.

NARRATOR: But what was unique about the presents or gifts

given to Father Crespi was that they often

took the form of elaborately carved artifacts...

...some made of gold or other precious metals.

Often, these objects featured elaborate carvings and symbols

not known to be associated with the Shuar culture.

In his 1973 book, Gold of the Gods,

ancient astronaut theorist Erich von Däniken

wrote of Father Crespi's incredible collection,

which he believed to come from the Cave of Tayos

and which were, in his opinion,

treasures from an unknown and highly advanced culture.

The startling questions posed in von Däniken's book

soon inspired Scottish explorer Stanley Hall

to try and solve the mystery himself.

In 1975, Hall traveled to Cuenca

to see Father Crespi's collection with his own eyes.

STANLEY HALL: I had for years been researching South America

as the missing page of, uh, prehistory.

I first heard of the... the Tayos Caves

was in Erich von Däniken's book

and followed it through from there.

VON DÄNIKEN: And one of the presents which the old priest received

is a tablet with 36 writings.

It's metallic tablet.

No one until today was able to translate these writings.

NARRATOR: In 1976, Stanley Hall mounted

an expedition of more than 100 people

to explore Tayos.

Among them was American astronaut Neil Armstrong,

the first man to walk on the Moon.

(helicopter blades whirring)

Entering the cave through a jungle entrance

known to the Ecuadorean army...

...the explorers were fascinated by what they encountered,

especially large areas that appeared

to have been excavated by someone.

Or something.

HALL: The head of the British geological group,

Dr. Brian Kelly, in 1976,

he admitted that it was difficult

for him to explain the actual large doorways

that you see in these caves.

MAN: Oh, yeah...

NARRATOR: Although Stan Hall's expedition

did find a tomb chamber with items dating to 1500 BC...

A ring. A stone ring.

NARRATOR: ...the expedition found no treasure

and no trace of anything that looked like the artifacts

in Father Crespi's collection.

But if Tayos was not the secret origin

of Father Crespi's amazing collection,

where did it come from?

Undaunted, Hall didn't give up his search.

15 years later, in 1991,

the explorer tracked down an Ecuadorean

named Petronio Jaramillo,

who claimed to have entered the Cave of Tayos

through a secret entrance back in 1946.

HALL: And apparently, Petronio had visited

this cave for the very first time

when he was very young, when he was in his teens.

He said that he had to dive underwater,

go in-in this underwater tunnel, and then come up.

NARRATOR: Jaramillo told Hall he wandered through chamber

after chamber of ancient relics,

including a vast room of books

made from gold and other metals.

Books with unrecognizable writing.

Possibly like that on one of the metal tablets

in Father Crespi's collection.

HALL: The other things looked like formulas.

And so on and so on.

So it was one spectacular statement after another.

(bird screeching)

COPPENS: Some argue whether or not an ancient civilization

had come down to Earth and had used this cave system

to leave certain artifacts of their civilization behind

for us to recover.

NARRATOR: Unfortunately, before he could guide Stanley Hall

to the underwater cave entrance, Petronio Jaramillo died...

...taking the secret to his grave.

Stanley Hall himself died in 2008

before he was able to renew his search

for the so-called metal library.

Fortunately, Stanley Hall's daughter Eileen

has decided to continue her father's work.

Unless we find this treasure, unless we can see,

translate the writing, it's still a big question mark

over who wrote it,

why they put it there and who put it there.

NARRATOR: But when Eileen Hall began to look for the location

of Father Crespi's original artifacts,

she learned that much of the priest's collection

had mysteriously vanished

shortly after his death in 1982.

But why?

Had Crespi's artifacts fallen prey to thieves?

Or might the Shuar have taken their treasure back

into the cave where they found it?

Whatever the answer, Eileen Hall has continued

to research other artifacts from elsewhere in Ecuador.

And like Father Crespi's objects,

some seem to have uncanny resemblances

to other cultures

that, according to mainstream archaeology,

ancient Ecuadoreans could not have had any knowledge of.

EILEEN: This collection is made up of what my father

believed to be the formative cultures of Ecuador.

This is from the coastal culture from 600 BC to 1600 AD.

And this is very humanlike, but at the same time,

some features have been exaggerated.

Here you've got the smaller face with the kind of bigger ears

and the elongated skull shape on the head.

The top of this head

looks like an elongated cranium,

an elongated skull, and it is identical

to this Egyptian statue

that we find all over Egypt.

To see this picture right here

and compare it to the Egyptian bust

we see right here,

it's uncanny.

The head shape is identical.

NARRATOR: Do Stanley Hall's artifacts

show evidence that Egyptian culture

could have crossed the ocean to influence

South American culture?

Or is it possible that both were influenced

by another culture?

One from beyond our world?

If so, were the strange writings

inscribed on Father Crespi's metal tablets

actual messages from an alien world?

My father went as far as saying

it was possibly an advanced civilization,

but we can't know for certain until this library is found.

So this metallic library is still there

in Ecuador in a subterranean cave.

There are still Indian tribes living there.

They are still protecting the old treasure.

COPPENS: So it's going to push the boundaries of academia

once this cave system has been found.

And whether it is Inca or extraterrestrial,

it doesn't really matter at this moment in time.

Let's get to this cave and see what is in there.

NARRATOR: Perhaps Tayos has yet to reveal all of its secrets,

but more than 700 miles to the north,

there is another cave,

one that may prove that the Mayan underworld

and the terrifying gods who ruled it

were not only very real but thirsty for human blood.

NARRATOR: The Yucatán Peninsula.

One of Mexico's premier tourist destinations.

Besides scenic beaches,

the area is covered by thick jungle

and pockmarked by massive sinkholes known as cenotes.

The ground beneath the jungle is also honeycombed with caves.

But here in 2007,

Mexican archaeologist Guillermo De Anda

found a cave like no other.

Following clues in the records of 17th-century Spanish priests

that hinted at the existence

of a mysterious underground Mayan temple

deep in the jungle...

...De Anda found a series of caves

near the village of Tahtzibichen.

Caves not seen for hundreds of years

and with entrances submerged beneath centuries

of floodwater.

GUILLERMO DE ANDA: Sometimes we have to dive into these caves.

Sometimes they got very deep.

The average of-of our research

is about 140, 150 feet.

But we know of caves much deeper than that.

NARRATOR: At first, De Anda and his team found

carved stone heads and broken pillars

with 1,900-year-old Mayan inscriptions.

DE ANDA: We have found columns under the water.

And these columns are amazing because some of them are

five feet high

and at least ten feet wide.

NARRATOR: But as De Anda surfaced in the dry areas of the cave,

he found what he believed to be the remains

of a massive underground temple complex...

...including a concrete road,

a crumbled pyramid and bones.

But why was it here?

The Mayans themselves have, uh, very intriguing, uh, legends

of an underground world called Xibalba.

And it's believed now by archaeologists

that what they found is what the Mayans thought

was the entrance to this legendary underground world

that features prominently in the Popul Vuh.

NARRATOR: Could this dark and mysterious cave

really be the underground world mentioned in the Mayan legends?

(birds chirping)

According to the Popul Vuh,

the written record of Mayan mythology,

the underworld kingdom of Xibalba,

meaning "the place of fear,"

was ruled by the cruel Lords of the Dead,

who made those who entered their realm

pass through a series of torture chambers

involving blood, darkness, cold,

knives, bats and jaguars.

(animal snarling)

MARTELL: We see here in this one archaeological spot

an actual physical representation

of what the Mayans felt the soul had to go through.

NARRATOR: Might, perhaps, this cave of stalactites

sharp enough to pierce flesh

represent the room of knives in the Popul Vuh?

There is also a room of bats

and a trench that might once have been filled with blood,

like the river of blood

that Mayan pilgrims had to cross over.

There are places of cold and darkness.

And even a room with the bones of jaguars.

(growls)

These caves were littered with large patches of spiders

and reptiles and all types of tumultuous things

that a human really wouldn't want to be exposed to.

NARRATOR: Although some archaeologists claim this unique site

was simply modeled after the description of Xibalba

in the Popul Vuh,

De Anda insists that items from the cave

date back to a time centuries before

the Mayan holy book was written.

DE ANDA: It's not that there was this document

and they tried to, uh, imitate what the document said.

I think it's all the other way around.

We believe that we have found the particular Xibalba

of the central part of Yucatán.

This is why we do believe it was a real place.

NARRATOR: But if Xibalba is real,

were the Lords of the Dead also real?

And if so, who or what were they?

TSOUKALOS: According to the Chilam Balam book,

which is the Book of the Jaguar Priests,

it says in there that at that time,

the road to the stars descended from the sky

and the 13 and nine gods came to Earth.

I'm sorry, "road to the stars descended from the sky"?

Can it be more clear? I don't think so.

Right there, we have a direct reference

to someone that has arrived from outer space,

and we have a written record about this.

NARRATOR: Could the Lords of Xibalba and other Mayan gods

really have been extraterrestrial travelers?

If so, why did they display such a thirst for blood and torture?

I do not believe human sacrifice

was originally taught by the ETs.

I believe it came in the aftermath

of when the original teachers of humankind had arrived.

The ancient gods,

which were really just humans from another world,

withdrew from the area,

and the people became distraught.

The more they became distraught,

the more they took the original mythology

and interpreted it in a much more literal way.

So what might have started out as the myth about the Sun dying

and being reborn when it sinks below the horizon,

becomes literally the idea of killing people

to make sure that the Sun is gonna come back up.

NARRATOR: As archaeologists and explorers

continue to uncover sites where legend and reality meet,

could there be even more evidence

that mankind's history on this planet

is much more profound than what we currently understand?

There are those who believe the secret

lies even deeper within the Earth.

As deep as its very core.

You can't talk about underground mysteries

without mentioning the Hollow Earth theory

that was proposed back in the 1600s.

Yeah, and personally, it doesn't really work for me,

but the moment that you change the word "hollow" to "inner,"

then all of a sudden, it makes sense to me.

Because we know for a fact

that gigantic chambers exist

underneath the Earth's crust.

Right. Then you have the writings of the Mayans,

the Buddhists, the Kabbalists.

They all speak of these multiple levels

beneath the Earth

that are inhabited by nonhuman entities.

We covered this in a 2015 episode

called "The Other Earth."

NARRATOR: Woolpit Village. The 12th century AD.

Two small children mysteriously appear

near the opening of a cave,

a boy and a girl speaking in a language

that is indecipherable.

But even more odd, their skin is green.

SABINA MAGLIOCCO: The farmers in the area who were harvesting vegetables

came upon these two children.

Their skin was green,

and their clothing was said to be made

of a strange fabric.

It was a fabric unfamiliar

to the people who were describing them.

KATHLEEN McGOWAN: The children are immediately whisked off

and put into isolation

from the rest of the village for several days

because no one is sure if they're actually human.

MAGLIOCCO: The children said that they came from the land of Saint Martin,

a land that was, in many ways, much like Earth.

They described the place that they came from

as not being as bright as our land is.

There was no bright sun, there was no dark night,

but it was a sort of twilit land

with the sky the color of early evening.

NARRATOR: Prominent 12th-century historian William of Newburgh

included a detailed account of the Green Children

in his major work History of English Affairs.

He noted that they eventually acclimated

to their new environment.

The children gradually became part of the community.

The-the boy, the-the younger of the two children, died,

but the girl survived, and there is

some serious tracking of her descendants,

indicating that she is a real person in history.

NARRATOR: Many theories have been proposed

as to where exactly these children came from.

McGOWAN: The most popular theory seems to be

that they came from another planet.

A planet with a different type of orbit,

a planet that was not exposed to the Sun.

NARRATOR: Does the well-documented account of the Green Children of Woolpit

give credence to the existence of another inhabited world

separate from our own?

Some ancient astronaut theorists suggest that another Earth

may exist not in space

but deep within the Earth, right under our feet.

June 13, 2014.

Scientists researching the Earth's mantle

announce that they have found what they believe

to be a vast body of water,

three times the volume of all of our oceans combined,

contained within a mineral layer

400 miles inside the Earth.

The discovery shakes the foundation

of what scientists and scholars thought they knew

about the ground under our feet.

We have just scratched the surface of the Earth.

Uh, we drilled down like eight miles,

and we had to stop because it got too hot.

Out of 4,000 miles,

basically to the core of the Earth, we went down eight.

That's nothing.

BROOKS AGNEW: We have more than 70

active space programs right now.

We can tell you more about the surface of the Moon

than we can the surface underneath our own oceans.

NARRATOR: Our scientific understanding

of the internal structure of the Earth

is primarily based on observations

of seismic waves generated during earthquakes

and knowledge of Earth's gravitation field.

Since we have not actually drilled down far enough

to confirm these findings,

could it be that we may be wrong

about the composition of our own Earth?

Some ancient astronaut theorists say yes

and suggest that according to our earliest mythologies,

an "other Earth" might not be found in the heavens

but deep within our own planet.

AGNEW: One of the most consistent themes that we find

in ancient cultures when we travel around the world

is the idea that there is another world,

another Earth, inside of the planet.

One of those is the Maya tradition.

They have a holy book called the Popol Vuh.

Inside this book, it talks about two twin boys

that came up out of the Earth

and were actually the first humans on the planet.

And to this day, they still believe

that life force comes from inside the planet,

not from outside in heaven.

The Mayans have this. The Tibetans have this.

The Hopi Indians have this.

CHILDRESS: Within Buddhism, there are stories

of a place called Agartha,

or Agharti, which is an inner world.

And it's inhabited, too, by people,

and that they are an advanced race,

and even that they have trains and vehicles that are moving

through this inner Earth.

ARIEL BAR TZADOK: The most ancient teachings share with us the shocking revelation

that the Garden of Eden

was on no place on the face of the Earth,

but rather, the Earth is hollow

and that the Garden of Eden

is an entire domain in inner Earth.

So are these stories literal?

There are those who believe that they are.

NARRATOR: Is it possible that an "other Earth"

can be located within the confines of our own planet?

Historically, underground realms

were not relegated to mere mythology.

Well-respected scientists and mathematicians

have long speculated about a theory

that became known as Hollow Earth.

MICHAEL DENNIN: The scientist Edmond Halley is most famous for Halley's Comet.

He was also very interested in the Earth,

and one of the challenges is... was trying to figure out

what was the real structure of the inside of the Earth.

He had a fascinating theory of not just a Hollow Earth

but an Earth with multiple layers

and many different atmospheres with many different layers

of land and earth circling and being concentric

as you went towards the center.

NARRATOR: 75 years later, 18th-century mathematician

Leonhard Euler put forth his own Hollow Earth theory

with no concentric shells and a sun at the center

spanning 600 miles.

AGNEW: Euler was a gifted mathematician.

He developed this idea that the planet Earth

is not only hollow, but the poles are actually thinned.

And there are actually entrances into the inner core

at the North and South Poles of the Earth.

He imagined that there were advanced civilizations

living inside the planet.

NARRATOR: Ideas of an occupied Hollow Earth would be revisited

nearly two centuries later, in 1947,

when famous polar explorer Admiral Richard Byrd

flew reconnaissance missions over the North Pole.

Byrd allegedly reported in his private journal

about a mysterious land beyond the North Pole,

which he called "the center of the great unknown."

I've always been a huge fan of Jules Verne,

and when he published A Journey to the Center of the Earth

in the late 19th century, this idea

of a whole other world inside the Earth

became a hot topic once again.

And then again in the mid-20th century,

when stories emerged about Navy Admiral Richard Byrd,

first pilot to fly over both the North and the South Pole.

Some accounts say he actually discovered an opening

into the Earth.

Yeah, I mean, this notion of beings

living inside the Earth persists even to today.

And we covered this in an early season two episode

of Ancient Aliens.

NARRATOR: The North Pole, a seemingly endless wasteland of arctic ice,

shrouded in darkness for six months of every year.

Here, there is no food, no shelter,

not even a cave to hide from the slashing winds

and temperatures that can dive to 90 degrees below zero.

But according to mainstream geology,

beneath the Pole and the Arctic Ocean

lies the Earth's mostly rocky crust,

up to 30 miles thick.

Below this is molten rock,

heated by the planet's spinning core,

with a solid center of iron and nickel the size of the Moon.

Scientists have deduced this information

from measurements of Earth's gravity,

magnetism and seismic waves.

But no one has ever seen these areas.

Could the frozen surface of the Pole be hiding a gateway

to a world within our surface world?

There are those who believe the answer is yes.

And what they believe is known as the Hollow Earth theory.

The Hollow Earth theory is that this Earth

is not molten inside-- it is actually hollow--

and that suspended in the hollow of the Earth is an inner sun.

NARRATOR: Surprisingly, the notion of a Hollow Earth

was first given scientific credence

by one of the founders of modern astronomy.

DAVID STANDISH: The idea that the Earth might be hollow,

as a scientific notion, dates back to the astronomer

Edmund Halley, who is best known for his comet.

In 1691, he presented to the London Royal Society

his, uh, hypothesis, uh, that the Earth, uh, is hollow.

He also suggested that these interior spheres

would also be able to support life.

NARRATOR: In 1818, former U.S. Army Captain John Cleves Symmes Jr.

announced that there were vast openings

at each pole where we could enter inner Earth.

With Symmes, the idea of a Hollow Earth

gets tied into exploring for the Pole.

At this point, nobody had actually seen Antarctica,

for instance.

NARRATOR: The Hollow Earth theory again captured

the public's imagination in 1864

with the release of Jules Verne's second novel,

A Journey to the Center of the Earth.

STANDISH: The novel takes an Icelandic guide

and a professor and a young man

down into the center of the Earth.

Journey to the Center of the Earth could really

have been called A Journey to the Center of Geology.

Geology and paleontology were a very hot topic

in the early 1860s, and there's a lot of discussion of that

in Journey to the Center of the Earth.

NARRATOR: But while Verne popularized the idea that extinct life-forms

might still exist inside the Earth,

others envisioned that the Earth contained

advanced underground civilizations.

CHILDRESS: Supposedly, they have advanced technology.

They've got ray guns and special weapons.

And even, they have flying saucers

and other craft like that.

NARRATOR: But is there any evidence

that such fantastic claims could be true?

And has anyone actually been to the world within our Earth?

Proponents of the Hollow Earth theory say yes,

and that one of the explorers was no less a luminary

than famed polar pioneer Admiral Richard E. Byrd.

In the 1920s, Byrd made world headlines

by flying over the North Pole

and by becoming the first man to fly solo over the South Pole.

But Hollow Earth theorists believe that the famous explorer

went even farther,

and that on February 19, 1947

Admiral Byrd piloted a plane

through a hole near the North Pole

into the interior of the Earth.

CLUFF: Flying saucer type craft took control of his airplane

with some kind of tractor beam.

And they landed him near an inner Earth city.

And the message that they had for us

was that they consider themselves

the guardians of this planet, okay?

He says, "We don't approve of you people

using nuclear weapons."

We had just blown up a couple of cities in Japan

a couple of years before,

so this was the message that he was given.

But when he got to Washington,

they put a lid of secrecy on this,

that this was not to go out.

NARRATOR: Some say Admiral Byrd's own account of this flight

into the Hollow Earth

is detailed in his secret diary, published in the 1990s,

almost four decades after his death.

But skeptics claim the diary is a forgery

and point out that in February 1947,

at the time Admiral Byrd was supposedly visiting

this other world underneath the North Pole,

he was actually part of a vast

4,700-man naval exploration called Operation High Jump

12,000 miles away near the South Pole.

But could Byrd's inclusion in this large military operation

at the South Pole have been merely a cover story?

Some people claim it was,

and this allowed him to slip away

to the other end of the planet, unnoticed by the media.

NOORY: Admiral Byrd, the rumor was, found a world

of flying machines and people and... more advanced than us.

And that they helped him, and then he left again.

It's a myth.

Nobody's really been able to prove it,

but it's a great myth.

NARRATOR: Could there really be vast, open spaces

within the Earth where advanced civilizations live?

Could extraterrestrial gods

really have come here centuries ago

and hidden the evidence of their journeys

deep within caves and tunnels?

Perhaps we have only just scratched the surface

of our planet's underground mysteries.

If so, what clues to our distant past

might still be waiting to be found

and hiding in the darkness?

Discovering things underground is very difficult,

but we're now getting technology that allows us

to see underground and find these hidden structures.

HENRY: Would you guys go into them?

Would you go into these deep underground...

-Yes. -I've... I've been in some.

-TSOUKALOS: Of course. -I've been in some. Yeah.

In-in Asia and in South America.

We tend to focus outwards into outer space

when we're looking for extraterrestrials,

but maybe we should really be focusing

underneath the surface of our Earth.

Our ancestors, the great cultures,

have always said, "As above, so below."

So, what more is there below?

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