Original subtitles

[Narrator] Enormous granite sarcophagi

that weigh more than 70 tons,

mysterious monoliths inspired by flying crafts,

and massive sphere-shaped stones that defy explanation.

♪ ♪

I've always said,

you know something is important if it is built out of stone.

Why? Because it could potentially last

for not just centuries but millennia,

and that's exactly what we see

in remarkable ancient constructions

that have withstood the test of time,

but in addition to the stone structures

we see around the world, there are also mysterious monuments,

strange objects,

and secret spaces that defy explanation,

like in the case of a stone settlement

that predates history as we know it.

[Narrator] Abu Shahrayn, Iraq.

6,000 years ago this ancient mound was the site of Eridu,

the oldest city of the Sumerian empire.

According to mainstream archaeologists,

this is the cradle of civilization.

[Felicia Beardsley] Many archaeologists will say

civilization began in Mesopotamia

some 6,000 years ago.

It is built on small bands of hunter-gatherers

who adopt agriculture.

The population starts to grow, and we begin to recognize,

we need to organize

our communities.

You start seeing these step-sided pyramids,

where the religious practitioner

might conduct his rites or rituals and so on,

and we have an urban planning environment.

That also means we've got a lot of engineering going on,

we have a lot of science, a lot of mathematics.

It has all of those elements we would call a civilization.

[Narrator] Many researchers around the world believe

there is evidence to suggest

civilization existed on Earth long before the Sumerians,

and one key source is the writing

of the Sumerians themselves.

Ancient cuneiform tablets list kings

who ruled tens of thousands of years ago...

...and they tell of an earlier age

when humans lived among powerful beings

that came down from the sky called the Anunnaki.

[Andrew Collins] The Anunnaki were the builder gods

behind the creation

of the civilizations of Sumer and Babylon.

They provided humanity with the rudiments of civilization.

They gave humanity animal husbandry

but also agriculture for the first time.

[Narrator] The Sumerians also wrote

that the Anunnaki were responsible for bringing

a devastating cataclysm upon the Earth...

[thunder cracks]

...eerily similar to the story that would later appear

in the Hebrew Bible as the Great Flood.

While nearly identical stories of a great deluge

can be found in the ancient texts

of many religions and cultures,

mainstream archaeologists had argued

that there was no evidence of any civilization

existing more than 6,000 years ago

to support the idea that such a cataclysm actually took place.

But in the early 1990s,

Klaus Schmidt of the German Archaeological Institute

began excavations at the ancient site

of Göbekli Tepe in Southeast Turkey,

and what he unearthed changed everything.

[Paul Bahn] Once Klaus Schmidt

started excavating Göbekli Tepe, it just blew everybody away

because we'd never before known or imagined even

that people 12,000 years ago

could produce such spectacular monumental structures

as he found at Göbekli Tepe.

[Tsoukalos] It is the first archaeological site in the world

that proves its age, dating as far back

as 12,000 years, around 10,000 BC.

The discovery and the official acceptance

of Göbekli Tepe's dating

has changed the history of archaeology.

[Robert Schoch] This is indications

of a major civilization

at that remote time,

a time when the standard historians all along have said,

"Well, no, civilization didn't occur at that time.

They were just simple hunter and gatherers.

They were primitive people."

But we now have evidence to the contrary.

[Bahn] It really did send shock waves

through the whole world of early prehistory

because we have never,

ever seen anything like this

from anywhere in the world

at that time, 12,000 years ago.

[Narrator] Göbekli Tepe's

nearly two dozen enormous T-shaped pillars,

some weighing more than 20 tons,

feature numerous carvings

that include depictions of animals, human hands,

and intricately designed symbols.

Archaeologists estimate that it would have taken

a team of 50 men an entire week

to move just one of the monolithic pillars

from the limestone quarry

to the top of the hill where they stand today

and over 300 hours to carve the bas-reliefs.

[Roy Fisher] The structures seem to reflect coordinated effort

among significant numbers of people,

which is not how we typically imagine

hunter-gatherer societies, which are usually smaller in size.

[Narrator] For years mainstream scholars maintained

that Göbekli Tepe was a completely unique site,

and while highly impressive,

it was not large enough to constitute

what would be considered a civilization.

But then, in 2004, author Andrew Collins

was shown photographs of a location

that looked remarkably similar to parts of Göbekli Tepe.

[Collins] I was visiting Göbekli Tepe, and some children

came up to me and showed me a picture

of this T-shaped standing stone with this snake along the side.

And I thought, "I've never seen this before.

Wh-Where is this?"

And it became clear that it was

some unexcavated site in the Tektek Mountains,

which is about 25 miles

away from Göbekli Tepe, and so I set out to find it,

and eventually I came to this bare limestone hill,

and as I walked up towards it, I could then see,

sticking out of the ground,

these heads of these T-shaped pillars--

again, exactly as you see at Göbekli Tepe--

and I realized that somewhere beneath this soil

was something as grand and spectacular as Göbekli Tepe.

[Narrator] For 15 years, only a small group of researchers

were aware of the pillars protruding from the earth

at the site known as Karahan Tepe.

When it was finally excavated,

archaeologists were shocked once again.

In 2019, digging begins.

And beneath the surface layers,

the archaeologists start uncovering

dozens of these T-shaped pillars.

[David Childress] You have about 200 of these T-shaped megaliths.

They're typically 13 feet high, weigh about 11 tons.

You have other phallic stones, you have

certain depictions of animals and some human faces as well.

So we have, really, a-a pretty extensive site.

[Narrator] The discovery of the vast megalithic complex

made headlines around the world,

as it was estimated by experts to have been inhabited

somewhere between 11,000 and 12,000 years ago,

just like Göbekli Tepe.

[Tsoukalos] Both Karahan Tepe and Göbekli Tepe

are striking in beauty,

striking in how massive and incredible

those megaliths are, and...

in my opinion they are related,

so it's also possible that at some point a long time ago,

that entire region was one gigantic city.

of the most mysterious monuments on Earth,

many of which tower over a hundred feet tall,

but deep within a forest in Bosnia,

several unusual monoliths have been discovered

that are not only massive,

they are almost perfect spheres.

[Narrator] Zavidovici, Bosnia, 1999.

Archaeologist Dr. Sam Osmanagich and a small team of researchers

are hiking along the Bosna River

when they come upon an astonishing sight.

In the midst of the dense forest are massive boulders

that do not appear to be a part of the natural landscape.

We discovered six of them intact, perfectly preserved

and perfectly spherical.

[Narrator] To Dr. Osmanagich,

the near-perfect shape of the objects is compelling.

[Osmanagich speaks foreign language]

And he begins to comb the region

in search of other stone spheres.

[Osmanagich] We have been researching

the stone spheres in Bosnia for 25 years,

and we have discovered 20 different locations.

The stone spheres in Bosnia come in four different materials--

granite, volcanic stone, sandstone and limestone--

and different sizes also.

In most cases they are over one ton.

[Narrator] After his initial discovery of the stone spheres,

Dr. Osmanagich expanded his search,

and in 2016 he spotted the most enormous stone sphere

he had ever seen hidden in the forest floor.

[Osmanagich] We could see that the small part

of the sphere was sticking out.

We started clearing it,

realizing that it was huge, monumental

in size.

Once we cleared almost all of it, we've done the measurements.

It is more than three meters in diameter.

The specific weight: 37 tons.

So this was the largest stone sphere discovery

in the world.

[Narrator] How the Bosnian stone spheres were created

remains a mystery.

Some geologists suggest they were shaped through erosion,

but others believe the spheres are simply too perfect

to have been formed naturally.

There is a process called

spherical, or spheroidal, weathering

that is very, very common.

We see them on the landscape in Arizona everywhere.

Called hoodoos.

You can see 'em out in Alabama Hills.

Out in Owens Valley there's a lot of examples

of this sort of sphere weathering,

but rarely are they perfect spheres,

and so it could be that some of these stones

started out mostly spheroidal

and then were worked into a more perfect sphere.

The one in particular that I'm thinking of, Bosnia,

that's been, um, in the headlines lately

has evidence of heat-treating to help facilitate polishing.

[McGowan] These are not just round stones.

They are 96% perfect

in their spherical form.

That's not something that's created by the earth.

[Narrator] The near-perfect measurements

of the stone spheres convinced Dr. Osmanagich

that they were carved by artificial means.

And in 2016 he sparked controversy when he announced

that he believed they originated with some unknown civilization.

[Osmanagich] Who made them?

We don't have precise answer, but we know that they were made

by ancient builders.

Why? Granite never

comes in spherical shape in nature.

[Narrator] If the stone spheres are not naturally formed,

as Dr. Osmanagich suggests, when were they made?

Many of the spheres are impossible

to scientifically date, but based on the layers of soil

where the largest stone sphere was discovered,

Dr. Osmanagich believes it is up to 100,000 years old.

We don't have very specific time,

but what we do know-- extremely old.

How do we know that?

The Bosnian stone spheres--

the biggest one is discovered below.

The tree-- 50 years.

Dark soil-- hundred years.

Light soil-- couple of hundred years.

We have light clay-- almost thousand years.

We have dark clay, we have gray clay--

tens of thousands of years.

And finally we have sandstone plate--

100,000-plus years.

[Narrator] Is it possible that the stone spheres in Bosnia

were created by some unknown culture

tens of thousands of years ago?

And if so, how?

[Osmanagich] According to the mainstream archaeologists,

until a couple of thousands of years back,

the only tools were copper tools.

Copper is soft material.

You cannot use copper tools to shape granite stones.

Of course this is us, 21st century civilization.

What did they use?

[Narrator] To try and understand how these artifacts were shaped,

Dr. Osmanagich had several samples taken from the spheres

analyzed in a lab

at the University of Belgrade in Serbia.

We realized that there is a difference

between their physical and chemical properties

and natural stone materials.

[McGowan] There is a chemical component

that was found within the spheres,

and this chemical has not been able to be identified.

[Narrator] If the giant stone spheres in Bosnia were created

by an ancient civilization, what purpose did they serve?

The precise engineering of the monoliths

and the fact that many are made of granite

has convinced Dr. Osmanagich

that the stone spheres' true purpose was to transmit

Earth energy that occurs in the region.

It seems that they had multilayer purpose.

According to the new science BioGeometry,

three most powerful geometrical shapes,

when it comes to the energy, are:

four-sided pyramid,

conical shape,

and the third one is the sphere.

Those three geometrical shapes amplify the energies.

[McGowan] Dr. Semir Osmanagic talks

about the use of these spheres as, potentially,

small power supplies,

and this makes sense when you look at them

in context with the rest of Bosnia.

When you're sitting in this creek bed

surrounded by these spheres,

it's hard to describe, but it does feel powerful.

It feels like it is generating energy.

20 miles south of the Great Pyramids of Giza

lies an astonishing structure called the Serapeum.

Built underground, the Serapeum is larger

than two football fields,

but the most extraordinary part of this subterranean complex

are two dozen giant stone boxes

that appear to have been created with advanced technology.

[Narrator] Saqqâra, Egypt.

Inside the mysterious subterranean structure

known as the Serapeum are 24 massive boxes

that are carved from exceptionally hard stone

like granite, basalt, and diorite.

[Ramy Romany] Each sarcophagus was over 70 tons.

70 tons is not a weight that 200 people can carry.

It is an impossible weight to move anywhere,

let alone a hundred feet under the ground

and then 700 feet into a tiny corridor

and then inside a little chamber.

[Colin Reader] If you think of a pyramid or a temple,

it's in the open air.

If you're hauling a big block of stone

or an obelisk,

you've got space to get teams of people.

You can get draft animals on it.

But the thing that really startles me--

they didn't have the space to get huge teams of men

to start moving them,

and they couldn't get animals down there

for any practical intent.

[Narrator] Just as baffling as how the ancient Egyptians

managed to move these giant boxes

is how they were able to carve them

with such incredible precision.

Machinists have gone in there with tools

to measure just how precisely carved they were.

We're talking, in some cases, to the thousandths of an inch,

right angles which are incredibly perfect.

[Tsoukalos] Now, you need sophisticated technology

for this because in some cases we're talking about basalt.

Basalt is harder than granite,

and according to what we know,

the ancient Egyptians only had bronze and copper tools.

It is wishful thinking to suggest

that you can cut basalt with copper.

You just can't do it.

But the surface is as if you're touching glass,

so, to me, it's possible that the ancient Egyptians

figured out a way to vitrify stone.

[Narrator] What compelled the ancient Egyptians

to place 24 enormous and precisely crafted stone boxes

deep beneath the earth?

Based on inscriptions found within the underground chamber,

Egyptologists determined that the Serapeum was built

to be the burial place of the sacred Apis bull.

[Salima Ikram] The ancient Egyptians believed

that animals and gods had special relationships

and each deity was associated with one particular animal.

The Apis bull is related to the Egyptian god Ptah,

who was a major creator god.

He was the god of Memphis, the capital city.

He was the god of all craftsmen.

The Apis bull was one of the most sacred animals

in all of ancient Egypt.

But here is the thing.

When August Mariette opened the sarcophagus,

they were empty, there was nothing in there.

[Childress] What Egyptologists will speculate is that

somehow the Serapeum was looted in antiquity

and the mummified bulls were removed from the sarcophagi.

But who would want a mummified bull?

[Narrator] Were the giant stone containers in the Serapeum

simply designed to hold the remains of an Apis bull?

Some researchers believe that these massive objects

served an entirely different purpose.

[Schoch] Most of these boxes have no inscriptions on them,

but there's one in particular that has a lot

of hieroglyphics all over it.

Those inscriptions are incredibly crude

compared to the finesse, the precision

of the actual stone boxes,

so this leads me, and I'm not alone in this,

to suggest that these boxes

go back to a much earlier period

and they were being reused and reappropriated

at a much later time.

It's thought by some researchers that the Serapeum was used

at a later date for the mummified Apis bulls,

but the Serapeum itself predates this

and its original purpose was for something else.

So what was the Serapeum for?

[Narrator] While the purpose of the stone boxes continues

to perplex researchers,

some believe clues can be found by examining the contents

of another box found in the Serapeum,

one not made of stone but wood.

[Narrator reads on-screen text]

[Narrator] After discovering 24 massive stone sarcophagi

within the Serapeum, Auguste Mariette

comes upon a much smaller coffin made of wood.

There is a body inside it,

and at first glance it appears human.

He came across a very unique burial.

It looked human.

And yet, when the bones were examined,

they were actually found to be those of a bull.

[Ikram] Mariette found no head of a bull

but just bits of bone of a bull wrapped up and then

sort of a mask of a human being on it.

[Narrator] Egyptologists assumed that the mask

must belong to the builder of the Serapeum

and determined the face it depicts

is that of a prince who lived in the 13th century BC

named Khaemweset.

[Ikram] People think that the person who built

the Serapeum was Prince Khaemweset.

Khaemweset was the fourth son of King Ramses II.

He was in charge of the temple of Ptah

and also, therefore, the temple of the Apis bull

in the capital city of Memphis.

[Narrator] Archaeologists also discovered evidence

that the only two bulls found in the Serapeum

were put there by Prince Khaemweset

around 1200 BC.

[Romany] He has a couple of sarcophagi down there

that he had put Apis bull mummies in them,

and he wrote that on a little tablet

next to that specific chamber

that he added to the place and he added to the Serapeum.

[Childress] This was a typical thing in ancient Egypt

because many of the monuments in Egypt were

thousands of years old, even for them,

so the idea that the Serapeum is actually much older

than even we think it is is a pretty valid theory.

Two of the largest monoliths on the planet

can be found in Japan,

and perhaps even more compelling

than the size of these mysterious monuments

are the local legends that say

they were created to honor otherworldly beings

who traveled in flying craft.

[Narrator] One of the greatest mysteries of the ancient world

is why enormous stone structures

appear on nearly every continent.

And at one time megalithic monuments

could be found throughout the islands of Japan.

[Jonathan Clements] Not many people know this,

but ancient Japan was strewn

with megaliths and henges.

The ancient peoples of Japan

had these stone monuments all over the place.

During the samurai era, which was war all the time,

most of them were ripped up and used to make castle walls

and castle foundations.

Some survived 'cause they're so weird.

[Narrator] Perhaps the most curious

and awe-inspiring of Japan's megaliths

is Ishi-no-Hoden,

a giant stone monument near Osaka

carved out of the bedrock

and believed to date back 16,000 years.

The Ishi-no-Hoden megalith is

sometimes called the heavenly floating rock.

It's huge, probably around 500 tons.

It's about a 20-foot square cube

that has been built in such a strange way

that underneath it,

there's a base that holds it up above the ground,

so it appears for all the world to be hovering in the air.

It is said to commemorate a god that once came to Earth

in a huge cubic-shaped object

and landed somewhere in that area.

[Tsoukalos] In Japanese mythologies and legends,

it says that long ago,

physical gods were amongst our ancestors

that had the capability of flying or of flight.

So the fact that they used this water mirror

underneath this stone

to show as if it is hovering and floating in the air,

to me,

is to signify flight.

[Narrator] Curiously, Ishi-no-Hoden

is not the only Japanese megalith

that appears to document

an ancient extraterrestrial visitation.

[Dominic Steavu] The Masuda-no-Iwafune,

which translates to "the stone ship of Masuda,"

is another megalithic structure.

This is an even larger granite, uh, megalith--

30 feet across and about 20 feet, uh, in width

and, uh, 15 or so in height--

that has a central depression, or trough.

[Phillips] This monolith is said to have marked the Earth side

of a so-called floating bridge

that connected Earth to the heavens.

Now, what is a floating bridge?

It's described as something that the gods descend in.

[Steavu] There is a story in Shinto annals

about the bridge that unites

the earthly realm with the heavenly realm

collapsing and falling onto the Earth.

So these megaliths, according to some,

are the remnants or the building blocks of this

celestial bridge that has since collapsed.

This floating bridge sounds exactly like

the bridge Bifröst of the Nordic tradition,

upon which the gods would come and go from the Earth

into the heavenly realms, or Asgard.

This suggests that the same people

are descending to these various cultures.

[Narrator] Might the Ishi-no-Hoden

and Masuda-no-Iwafune megaliths

have an extraterrestrial connection?

Ancient astronaut theorists say yes

and suggest the most intriguing of Japan's megalithic structures

can be found beneath the sea.

On the western tip of the Japanese archipelago

lies the tiny island of Yonaguni.

In 1986,

scuba divers exploring just off the coast

make a shocking discovery.

60 feet beneath the ocean surface,

they find a massive rectangular structure

roughly 328 feet long

and 196 feet wide.

It has since become known as the Yonaguni Monument.

[Phillips] The Yonaguni Monument is huge,

and it looks for all the world like an artificial construction.

There are steps,

there are what appear to be columns

and all sorts of geometric formations

that seem to have been artificial constructions.

Professor Masaaki Kimura spent ten years

examining the structure with divers

and the most sophisticated equipment at the time,

and he was convinced beyond any doubt

that it was an artificial formation.

[Tsoukalos] Yonaguni boggles the mind

because at some point

that was a land bridge that existed

when the water levels were lower,

and that means we're talking around the last ice age,

which was 10,000 or so BC.

Now, that means that back then

a culture must have existed

to carve Yonaguni the way it appears today.

For ancient astronaut theorists,

the mythology found throughout ancient cultures

of sky gods visiting Earth to instruct humans

could be evidence of our ancestors

witnessing misunderstood extraterrestrial technology.

For example, a 3,000-year-old stone carving

found in Mesoamerica

looks so much like a pilot in a cockpit

that this mysterious monument is often called

the La Venta Astronaut.

[Narrator] Teotihuacán, Mexico.

At the southern end of this ancient metropolis

stands the Temple of the Feathered Serpent.

Its magnificent facade is embellished

with numerous ornate stone statues

of a snake head ringed in feathers.

This visage depicts one of the most prominent gods

worshipped throughout Mesoamerica,

a being known to the Aztecs as Quetzalcoatl.

[Barnhart] Quetzalcoatl was

undoubtedly one of the major gods

for multiple civilizations in Mesoamerica.

A particular characteristic of the Quetzalcoatl

is the feathers on the bottom of his body

that really denote the deity.

Quetzalcoatl is one of the,

if not the primary Mesoamerican god.

He's a god of light, a god of wisdom,

a god of healing,

and ultimately a peacemaker.

[Narrator] In their codices, the Aztecs write about

Quetzalcoatl teaching their ancestors

various disciplines that were essential

to establishing their vast civilization.

Quetzalcoatl descended from the sky

in physical form and taught the local populations

in different scientific disciplines

like mathematics...

...agriculture, medicine,

writing, all these different things.

It's interesting to see that this is not the only place

where, in ancient mythology, the same takes place.

Because there are other cultures around the world that also refer

to teacher gods who descended from the sky.

[Narrator] Throughout the ancient world,

stories can be found of powerful beings

who came from the stars

and shared wisdom with early humans

to help jump-start civilization.

In Egypt, the god Ptah shared knowledge

of technology and metalworking.

Prometheus taught the ancient Greeks

how to wield fire.

And the world's first civilization,

the Sumerians, wrote that they were visited

by divine teachers known as the Anunnaki.

[Amir Hussain] In the Sumerian tradition,

one of the gods, Enlil,

teaches human beings about agriculture,

teaches human beings how to plow into the ground and plant seeds.

It's the gods who show human beings

how to use technology, how to create this technology.

[Tsoukalos] This idea that there were teacher gods

a long time ago,

the ancient astronaut theory suggests

that our ancestors were all visited by the same teachers.

The same extraterrestrials.

[Narrator] Could Quetzalcoatl

represent an extraterrestrial visitor

who helped to establish civilization in Mesoamerica?

According to ancient astronaut theorists,

support for this notion can be found

not only in the Aztec codices

but also by examining a number of curious depictions

of the Feathered Serpent god.

La Venta, Mexico.

1955.

American archaeologists Philip Drucker and Robert Heizer

begin an excavation of an Olmec pyramid mound.

North of the main pyramid,

they unearth a mysterious carved stela

that they date to around 1200 BC.

Now known as Monument 19,

it is believed by many to be the oldest depiction

of Quetzalcoatl ever discovered.

[Barnhart] La Venta Monument 19

is such an interesting and evocative piece of art

that it's gotten a ton of names.

One of them is the Rocket Man.

[Tsoukalos] It depicts this weird scenery

of some guy enclosed inside a snake,

and it's as if he's sitting on some sort of a seat.

The guy's, you know, wearing some sort of a suit

with a helmet,

and he is, you know, just sitting inside this enclosure.

In my opinion, it's an example of misunderstood technology.

Monument 19 is a representation

of Quetzalcoatl, the teacher god,

inside of a flying craft.

[Narrator] Does Monument 19's unique depiction

of Quetzalcoatl, not as a feathered serpent

but as a humanlike figure

sitting within the body of a serpent,

provide further evidence

that he was a real-life visitor from another world?

Curiously, the Olmecs weren't the only people

to depict Quetzalcoatl in human form.

There are also Maya and Aztec depictions of Quetzalcoatl

that show a human face

seeming to emerge from the mouth of a serpent.

[Von Däniken] Now, according to Central American tradition,

Quetzalcoatl is supposed to have descended from a star.

He's represented as the Feathered Serpent,

but also he's represented

in the human form with the helmet.

There are many of these representations of Quetzalcoatl.

Quetzalcoatl was definitely an extraterrestrial.

High in the mountains of Peru

stands one of the most mysterious monuments on Earth.

It's an ancient fortress

with walls built from gigantic stones

that are joined so tightly,

it'd be difficult to recreate them today.

But for some researchers, the most compelling question

isn't how this structure was created

but, rather, when.

[Narrator] Cusco, Peru.

Nestled in a high river valley of the Andes Mountains,

among peaks towering over 20,000 feet,

this once-great city served as the capital

of the Inca Empire

from the 13th to 16th centuries AD.

In 1533, Spanish conquistadors arrived in Cusco

and were astonished by the incredible stonework

found at a site just north of the city called Sacsayhuamán.

[Brien Foerster] Above the city of Cusco, we find

the megalithic site and huge ceremonial Inca complex

called Sacsayhuamán.

Its most prominent feature is a zigzag wall of three levels.

Some of the stones there weigh as much as 125 tons

and were moved from the quarry at least three miles away.

[Tsoukalos] Sacsayhuamán

is one of the most beautiful ancient structures

you will ever see in your life.

There are massive, gigantic megalithic blocks,

and you find the most amazing of masonry style

where you can't even fit a dollar bill

in between the fittings of any of the blocks.

[Narrator] Sacsayhuamán served both as a fortress

and a ceremonial center.

A circular structure that lies within the megalithic walls,

called Muyuq Marka, was the base of a tower

where the Inca worshipped the sun god Inti.

However, many experts suggest that while the Inca

certainly utilized this megalithic structure,

they were not the ones to build it.

[Foerster] Standard belief is that

the Inca constructed Sacsayhuamán

less than a thousand years ago.

But some of the earliest Spanish chronicles, it is said

that the Spanish were completely astounded

by seeing this site, and they asked the local Inca,

"Did you build it?" and the Inca replied, "No.

This was here when we arrived 500 years ago."

[Narrator] Many experts believe Sacsayhuamán predates the Inca

by thousands of years

and that the Inca built on top of what came before.

[Foerster] The Inca were

a Bronze Age civilization,

and the stones at Sacsayhuamán

are metamorphosed limestone,

which is much harder than bronze

and could not be cut or shaped using bronze tools.

Inca built on top

'cause you can tell a major difference

between megalithic construction,

where the stones fit perfectly together,

and the Inca, which is stones piled on top of stones

with mortar as filler.

[Narrator] But if Sacsayhuamán really does predate the Inca,

as the Inca themselves claimed,

how could an even earlier civilization

have possessed far superior technology?

[Tsoukalos] The ancient Inca talk about

celestial beings who descended from the sky a long time ago

and imparted the first knowledge of anything

toward people of Earth.

The ancient astronaut theory suggests

it was human beings who built Sacsayhuamán

but under the tutelage of the extraterrestrials.

The remarkable engineering

of the stone walls at Sacsayhuamán

is just one of many fascinating enigmas

that the ancient Peruvian site holds.

And as we've seen, mysterious monuments

come in all shapes and sizes.

From colossal megaliths in Japan

and baffling stone spheres in Bosnia

to giant stone boxes in Egypt,

what they all have in common is that

they were created to last for thousands of years,

perhaps to honor or to immortalize

extraterrestrial contact in the distant past.

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