Original subtitles

WILLIAM SHATNER: An opulent island nation destroyed by the gods.

Stone tablets that point to

a complex in the middle of the ocean.

And massive rock monoliths that may reveal

a lost civilization.

It's remarkable to be living in the 21st century

and to be surrounded by the ruins

of ancient civilizations. And all around us

are the remnants of great cultures

who, for thousands of years,

created sophisticated communities

and complex societies.

The history of our ancestors is still a puzzle

we try to solve by piecing together

written records and stone monuments

and buried artifacts.

What secrets might be uncovered

hidden beneath our feet and in the depths of our watery oceans?

Well, that is what we'll try and find out.

♪ ♪

Within this modern city stands the ruins

of a citadel that was once the center of Ancient Greece.

The Ancient Greek civilization lasted

for more than three centuries.

The Greeks developed a sophisticated culture,

which had a profound impact on Western politics,

science and philosophy.

One of the best known Greek philosophers was Plato,

who wrote more than 20 important philosophical texts

known as "dialogues."

RIC RADER: Plato was doing his major writing

in the fourth century BCE,

and Plato's works are very serious,

very sober philosophical reflections

on major, major questions.

He is really the most important philosopher

in the Western world.

RICHARD FREUND: For most of Western civilization, Plato is the basis

for our thinking and philosophy,

but he's also partially historian.

And his work is still used

in order to identify the way life was in antiquity.

SHATNER: Of all the influential writings of Plato,

the one that is perhaps the most fascinating

and the most mysterious

is his account of a lost civilization that existed

centuries before the rise of Ancient Greece.

Atlantis.

Atlantis is a very important story in Western imagination.

In the year 359, before the Common Era,

Plato, the great philosopher, told a story

about a continent, a large island

out in the Atlantic Ocean.

And it became a very powerful nation.

It was home to a fabulous civilization

that began as the byword for justice and compassion.

It had a huge navy that it used to travel

from place to place around the Mediterranean.

ANDREW COLLINS: Plato tells us in his dialogues that the information came from

a famous statesman who visited Egypt

by the name of Solon, a few centuries before.

SHATNER: Plato wrote that Solon traveled to northern Egypt,

and entered a sacred temple

dedicated to the Egyptian goddess Neith.

Within the temple was a column

completely covered with hieroglyphics,

on which the history of Atlantis was recorded.

Egyptian priests told Solon

the story of this lost civilization,

which predated the Egyptians themselves.

Egyptians would recount the story of Atlantis

as a major, major part of where their civilization came from,

where they got a lot of their knowledge.

This was a very advanced and technological civilization

and Plato was reporting this as a very,

very important story for the ancient Egyptians.

Pretty much, like, the next day after Plato writes this,

people start debating whether or not it was true.

Did Plato mean this as a fictional story

or was Plato talking about a historical occurrence?

SHATNER: While it may sound like the stuff of fantasy,

in his dialogues Timaeus and Critias,

Plato provides a wealth of detail about what many believe

was a very real island nation.

HUGH NEWMAN: Plato described Atlantis as being a huge landmass,

potentially in the Atlantic Ocean.

One of the main design specs of Atlantis was this huge area

at the center of the main city of Atlantis

that had concentric circles of land and canals.

It had a canal coming out that went to the sea and

a great port was built there.

YOUNG: The concentric circles of navigable canals suggest

a well-planned early marina.

It is strongly oriented to the sea.

In the temple, on the acropolis at the center of Atlantis

there is a statue of Poseidon, the creator god of the place.

And he's got winged horses,

a chariot with horses that can fly.

So, there is also a transcendent dimension implied.

SHATNER: But if such a transcendent, awe-inspiring place

actually existed, what happened to it?

According to Plato, the Atlanteans angered the gods

with their pride-- what the Greeks called "hubris."

And you definitely don't want to do that.

YOUNG: Atlantis got more and more vain,

more and more abusive in their hubris,

a kind of arrogance that was saying, "We are gods."

That vanity of thinking that we are as important

as the gods tends to upset the gods

and then the downfall comes, the downfall that

is in every Greek tragic play is the same thing.

People of great privilege are brought down.

Atlantis disappeared in a day and a night

due to some natural catastrophe, and it ended up under the waves.

YOUNG: The gods came and destroyed the whole place.

The people were killed, the navy was destroyed, all in a day.

And Atlantis sinks into the sea.

When Plato talks about this catastrophic destruction

of Atlantis, I have to take him seriously.

And people would say, "Oh, it's just a metaphor, Atlantis."

Every metaphor has at its base

a nucleus of historical information.

So even if he fictionalized it, even if he elaborated it,

at its nucleus, it's a real historical place.

SHATNER: Obviously, the best way to prove whether or not Atlantis exists

is to find it.

And rediscovering mythological cities

isn't as far-fetched as it might sound.

Other than the myth of Atlantis, the other great myth

was the existence of Troy...

...a city that rivaled the Greeks in power.

We know about the Trojan horse.

We know about Helen of Troy. We know about Achilles.

SHATNER: For centuries, scholars scoffed at the notion

that Troy was a real place.

That is, until amateur archaeologist

Heinrich Schliemann went looking for it in 1871.

And believe it or not, Schliemann found Troy,

pretty much where Homer said it would be.

KAKU: And that spawned a whole industry

of trying to find other ancient cities.

But I think it also raised false hopes

that we would find Atlantis

the same way we found the city of Troy.

It may not be so easy.

SHATNER: The modern search for Atlantis was kicked off

back in the late 19th century by a rather curious

amateur scientist named Ignatius Donnelly.

CHRISTOPHER BADER: Ignatius Donnelly wrote a book called

Atlantis: The Antediluvian World

back in 1882.

And this was a book that really brought Atlantis

out of Plato's fables and into modern consciousness.

He said Atlantis really existed,

really did have advanced technology.

SHATNER: For Donnelly, researching the story of Atlantis

became such an obsession

that he even went so far as to claim that he knew precisely

where Atlantis would one day be found.

YOUNG: Ignatius Donnelly said Atlantis was in

a very specific place in the Atlantic Ocean,

that it sank and that the Azores--

the islands out there off Spain--

are the tips of the mountains.

Now we have good undersea exploration.

We can go down and see the heavy silt

that is at the ocean bottom that took

millions of years to build up.

It couldn't have been a civilization

that sank a few thousand years ago.

So he was wrong.

But Ignatius Donnelly advanced the idea

that Atlantis may have physical history to it.

SHATNER: Many researchers believe that the best way

to find Atlantis is to look for it

where Plato said it was located.

FREUND: Plato gives us very specific geographic locations

for where Atlantis was.

He says it's by the Pillars of Hercules.

And the pillars were actually two mountains,

one located at the Rock of Gibraltar

and the other located in Morocco.

And these two rocks were the Pillars of Hercules.

So, he's putting it in a very specific location

that every single reader knew about.

SHATNER: Do the ruins of the legendary city of Atlantis

lie deep beneath the Mediterranean Sea?

It's an intriguing thought,

and not completely outside the realm of possibility

when you consider the mystery surrounding

an abandoned tropical complex that may be the home of

the lost continent of Mu.

SHATNER: A team of geologists at GNS Science

announce a major discovery

related to the Earth's continents,

the vast landmasses that make up the planet's surface.

The scientists found that, in addition to the seven continents

that humans have known about for centuries,

there's also an eighth continent located directly

underneath New Zealand, which they named Zealandia.

Zealandia sank into the ocean

approximately 50 million years ago,

and its existence suggests that there may be

even more lost continents that were swallowed up by the sea.

The Earth has cycles of sea level rise

and sea level fall.

Over the last hundreds of millions of years,

as climate has warmed, we get sea level rise.

Cold periods, sea level fall.

There's a huge amount of land which is now covered by the sea.

Ten thousand years ago, with the end of the Ice Age,

sea levels were dramatically lower than they are now.

And because of the melting of the ice,

sea levels have risen since then

and cities that may have existed thousands of years ago

could be lost in history as a consequence.

SHATNER: For thousands of years, cultures from around the world

have told stories about long-lost continents

that were home to human civilizations

and are now submerged beneath the waves.

Perhaps the most famous is the legend of Atlantis,

a massive island that was home to an advanced civilization,

before it supposedly sank into the ocean after an earthquake.

NEWMAN: There's been more books written about Atlantis than

any other lost continent in history.

There are many sunken cities, lost lands,

destroyed continents, all around the planet

in legend and history.

For example, we have the lost land of Hy Brasil,

which was thought to be 200 miles off the coast of Ireland.

And it was even on maps until the 1800s.

SHATNER: One of the most intriguing lost continents

is a landmass that is believed

to have once existed in the Pacific Ocean.

A mythical land that is known as Mu.

The first person to write extensively

about the lost continent of Mu

was a Scottish writer

by the name of James Churchward.

In the 19th century, he was in India

when he visited a monastery.

And the monks there had records, apparently,

tablets that referred to this place called Mu

that was this huge continent that supposedly existed

from Hawaii in the north

down to Easter Island in the southeast,

right the way across to Micronesia in the west.

And the people there were supposedly called the Naacal.

The continent of Mu thrived

perhaps 50,000 years ago

and was sunk beneath the waves,

possibly at the end of the last ice age.

My great-grandfather, James Churchward--

eventually, he became friends with the rishi of the temple

that he visited in India.

And the rishi mentioned that he was

a member of the Naacal brotherhood,

the holders of wisdom and knowledge

of the lost continent of Mu.

They were mighty navigators and sailors

and established civilization in other parts of the world.

SHATNER: According to James Churchward,

the Naacal civilization had a population

of more than 60 million people at its peak,

before a massive volcanic cataclysm

caused Mu to vanish beneath the waters.

So far, no evidence of the lost continent

has been found on the ocean floor.

But some researchers claim that, incredibly,

a tiny remnant of Mu may still exist above water today

on an island located

in a remote part of the Pacific Ocean.

Roughly 2,500 miles northeast of Australia

lie the ruins of a once great ancient city: Nan Madol.

Nan Madol is a complex of man-made islands

built with massive stone blocks

that float atop a submerged coral reef.

COLLINS: So, as you approach Nan Madol,

there are a series of islands,

and they're built actually on coral,

the only place in the world where this actually occurs.

And you've got all these incredible structures

made of these prismatic blocks.

At Nan Madol, you have these ridiculous basalt columns.

They're huge, some of them, up to, like, 40 tons,

even more, in some cases.

Some of them are raised very high up in the air,

on the very top levels.

So there's a real problem when it comes to

try and understand how they moved

these millions of tons of basalt columns.

One of the biggest mysteries surrounding Nan Madol

is that nobody really knows who constructed it.

But there's some very strange stories about

how the city came into existence.

For instance, one of the stories talks about

it being constructed by so-called master builders

turning up and using a magical force

to raise the blocks into the air and put them into place,

almost as if they could levitate these blocks.

Some people actually suggested that maybe Nan Madol

was the last remnant of Mu

that was still above water,

and it was simply indicative of

what had sunk beneath the waves

from this advanced civilization.

Nan Madol is in Micronesia,

so it fit the correct general area.

And this is one reason people thought in terms of Mu.

NEWMAN: When it comes to looking for this lost continent of Mu,

places like Nan Madol really do suggest

there could be much more down there than we realize

on the bottom of the ocean.

SHATNER: It's exciting to think that the study of Nan Madol

could one day shed light

on who built these extraordinary structures

and where they may have disappeared to.

Such is the case a half a world away in Sardinia,

where elaborate carvings,

strange statues and massive tombs

may soon reveal the identity of an ancient race

of giants.

SHATNER: On this island located off the coast of Italy,

a farmer in a region known as Mont'e Prama

is tilling his fields when he strikes

what appears to be a large rock.

But upon closer inspection, he realizes that his plow

has revealed something far more amazing.

It's the head of a massive, ancient statue.

The farmer started digging around it,

brushing away the mud, pulled it out,

and there was this giant stone head gazing back at him

with these obsidian eyes.

And so this became quite a sensation at the time.

It was one of the most important

archaeological discoveries of the decade.

EDWIN BARNHART: Subsequently, archaeologists entered the area,

and through the late 70s,

they dug and they found over 5,000 fragments

of these giant statues.

We have archers, we have warriors, we have boxers.

They are, generally speaking, about eight feet tall,

and approach a ton in weight.

And they are unique in the regard

that for their time, there was

no other statuary that was in human form and size

and that level of detail and sophistication.

SHATNER: The monolithic statues came to be known

as the Giants of Mont'e Prama.

According to archaeologists, they were carved by

the Nuragic people, a mysterious civilization

that lived on Sardinia nearly 4,000 years ago.

The Nuragic people were the indigenous population

of Sardinia, beginning around 1750 BCE.

And they were not the kind of society that would have writing.

So, we don't know a lot beyond their everyday lifestyle,

which would be, in many ways, similar to what was going on

throughout the Mediterranean at the same time.

SHATNER: Incredibly, some researchers claim that the reason

why the Nuragic people carved statues

that were eight feet tall

is because these monoliths

were created in the image

of an actual race of giants.

NEWMAN: One of the strange things about these statues

is that they appear to be buried

underneath these kind of slabs of stone

in this elongated grave, as though they were

almost like ancestors being buried in the ground.

Why they did this, we don't know.

But there are many legends of giants

all over Sardinia and the stories go on and on and on.

So, these could be the same giants who were

memorialized in these particular statues.

SHATNER: Could the monoliths of Mont'e Prama really be evidence

that a civilization of giants

once inhabited the island of Sardinia, as some believe?

Many researchers think that it's possible,

and claim that there are additional clues in folklore

throughout the Mediterranean.

LaCROIX: Diodorus, an ancient Greek historian,

discussed how there was an ancient bloodline

of the Athenian civilization

known as the 50 sons of Hercules that mated

with a mortal race of women to create a giant bloodline

that built these monolithic statues

on the island of Sardinia.

NEWMAN: This story really put the idea

into different philosopher's heads that

this was actually a very advanced culture

that kind of led up to the time of the Nuragic people

and culminated in the era of the Mont'e Prama giants.

SHATNER: The massive monoliths of Mont'e Prama

and stories from folklore aren't the only pieces of evidence

to suggest that giants once lived on Sardinia.

Because there are also mysterious tombs

located throughout the island that may have been

where their oversized bodies were buried.

TYKOT: What we see at Mont'e Prama

are totally separate structures

for where they buried their deceased,

and these are called the giants' tombs, tomba dei giganti.

They are typically made of one very large stone

that have a semi-hemispherical

entry area or front

that curves inward

with the center part having a small hole down at the bottom,

which is where the skeleton would have been interred.

NEWMAN: As you see these giants' tombs, what you realize is

that it's entirely made of large blocks

with a small opening in the base.

In tradition, these were the burial places

designed for giants, and they would actually

build a tomb around it.

This is one of the clues

that kind of links with the legends

that giants did exist in Sardinia.

But there is further evidence that actual skeletons

have been found in some of these giants' graves.

We have accounts, from 1901,

where there's a report of four nine-foot skeletons

being unearthed in the vicinity in northern Sardinia.

And even relatively recently,

there are reports of three skeletons being dug up

in an area called Torralba, in southwest Sardinia.

However, the problem is is that most of the evidence

has now disappeared.

They've just gone missing, basically.

And so, you have to question, why is this?

Is there a cover-up?

SHATNER: Is it possible that the bones of giants

have actually been hidden from the public?

It's an intriguing theory,

and it deepens the mystery surrounding

the strange, towering statues uncovered at Mont'e Prama.

BARNHART: The Giants of Mont'e Prama

are very unique and enigmatic,

and Sardinia's myths and stories

about who these people were typically talk about giants.

But there's a lot of things we don't know

about who these people were.

And so, these giant statues

are the mystery within that mystery.

Are the tombs discovered on the island of Sardinia

the final resting place of actual giants?

While some may be wary of such a conclusion,

our ancestors certainly went to great lengths

to carve and construct massive structures out of stone.

Like in the case of a remote island in the Pacific Ocean

whose picturesque landscape is covered

with mysterious colossal monoliths.

SHATNER: 2,300 miles off the coast of Chile,

an island rises from the waters of the Pacific Ocean.

Called Rapa Nui by the locals,

the island is perhaps better known by the name given to it

by Dutch explorer Jacob Roggeveen

when he landed here on Easter Sunday,

April 5th, 1722

and dubbed it Easter Island.

Today, some 5,000 people make their home here,

most of whom are the descendants

of Easter Island's original inhabitants,

who were also named the Rapa Nui.

But its most famous residents are the hundreds of massive,

ancient monolithic statues known as moai

that are scattered across its grassy cliffs.

Easter Island is famous for its moai statues.

They are these human depictions.

Their faces are very long and their chins are long

and there are over 900 of them on the island.

About 95% of them were quarried at a crater

called Rano Raraku,

and there are a number

of failed or just "given up on" moai

still carved into the crater's face.

The moai vary quite a bit in size, but the average moai

is about 12 to 13 tons and about 13 feet tall.

So, people are really fascinated by this,

and continue to beg for an explanation

of why did the ancient islanders

in this remote location invest so much

in these giant statues, and why are they here?

SHATNER: Archaeologists estimate that the moai

were created between 1400 and 1600 AD.

For centuries, experts have been confounded

as to what these massive headstones

were intended to represent.

But then, in 2010, archaeologists uncovered

an important clue when a series of excavations revealed

that there was more to the moai than meets the eye.

SCHOCH: They discovered the moai have torsos.

And they have very long, thin arms and hands.

They're huge statues, and they're buried up to

their necks, literally, in sediment and debris.

HUNT: The moai have details on the body.

Some have petroglyphs on the body.

And people are really fascinated by this,

because the common misperception of the moai

comes from the really

iconic photos of the heads alone.

So, people see that and they just call them heads,

but it's correct to really refer to the moai as statues.

SHATNER: The discovery of the full-sized moai statues

only deepens the mystery surrounding them.

The revelation that some of these monoliths are more than

twice as big as previously believed

naturally begs the question,

how did the Rapa Nui move the massive stones into place?

The transport of these giant statues

has been a continuing mystery.

For example, the largest moai ever transported

goes by the name of Paro.

Paro is about 33 feet tall,

and he's estimated to weigh about 75 to 80 tons.

Paro was transported from the quarry to the platform

where he was displayed, and it's over three miles.

So, it's an amazing accomplishment.

BARNHART: The mystery of how they moved these giant statues

has been a perennial question.

When the first Europeans showed up and

asked the local people how they did it,

they said, "Well, the statues walked there themselves.

"They walked from the quarry to these platforms

they stand on called ahu."

And so if we listen to the Rapa Nui,

there was a magical quality to creating these moai.

SHATNER: Is it possible that the moai somehow walked into place?

Of course, it sounds impossible,

but according to tests conducted by archaeologists in 2012,

there may be some truth to this legend.

What we showed in experiments,

with a replica of an actual moai,

is that the statues have a lower center of gravity

that makes them lean forward.

And if you attach ropes to the head

and rock the statue,

the pendulum effect takes over,

allowing it to fall forward,

and the statue actually walks.

BARNHART: It turns out that it looks like, in the end,

the Rapa Nui may well be right. Maybe they did walk there.

SHATNER: Were the moai statues moved by an ingenious use of ropes?

It's just one of the many intriguing theories

about these giant stone statues.

But ultimately, how they were transported

and became buried up to their necks

remains unknown.

The moai of Easter Island really have come to represent mystery.

Huge stone sculptures

on a grassy, windswept island--

people wonder who made these and why.

And so the mystery continues.

SHATNER: The revelation that some of the buried moai of Easter Island

had full-sized bodies adds a new wrinkle to the theories

about why they were designed in the first place.

Perhaps it's when we dig deeper into the Earth

that the true stories from the ancient past

are finally revealed.

Like in the case of an ancient complex

in the heart of North America,

where a deadly ritual may have led to the demise

of an entire civilization.

SHATNER: In the heart of the downtown district

stands the Wainwright Building.

Built in 1891, this office building

is one of the world's first modern skyscrapers.

But as it turns out,

there is a similarly sized structure in this region

that is much, much older.

Just ten miles east of the city

stand the ruins of an ancient, man-made pyramid mound

that was built centuries ago

and is as tall as a ten-story building.

This is the largest prehistoric earthwork

in the western hemisphere,

the largest totally earthen mound built by ancient people

in North or South America.

Its base, actually, is bigger than the Great Pyramid in Egypt

and it stands 100 feet high.

And it was built with about 22 million

cubic feet of dirt that had to be

carried in baskets on people's backs and deposited.

SHATNER: The fact that the ruins of a man-made pyramid

sit in the middle of the United States

might come as a surprise for some.

And yet this monumental earthen mound is merely one

of more than a hundred similar structures

that have been discovered in this area.

They are all part of a sprawling ancient city

named Cahokia.

Cahokia is arguably the most important

of the ancient cities of North America.

Constructed approximately between 700 and 1350 AD,

it was an incredible metropolis.

We have this idea of the first peoples

as being hunter-gatherers

and riding around on horses all the time,

and that's simply the wrong impression.

They were an incredibly technologically

sophisticated society.

ISEMINGER: We don't know what this place was called

or what the language the people spoke here.

The name Cahokia comes from a later group

of American Indians that moved into this area in the 1600s

from further north, around the Great Lakes.

They were here, but they did not build the mounds.

They just later used it as part of their settlement.

We often use the term "city" when we talk about Cahokia

because of its magnitude.

It covered nearly six square miles, or about 4,000 acres.

During its peak, between 1050 and 1150 AD,

there were probably, you know, 40, 50,000 people

living within this region.

It would be larger than London was at that time.

And yet, 200 years later,

by 1350 AD,

the whole place had been abandoned.

And indeed, there is a mystery

of exactly what took place there.

SHATNER: But if Cahokia was such a thriving metropolis,

then it begs the question--

how did this civilization come to an end?

It's a mystery that has driven archaeologists

to scour Cahokia's ruins in search of an answer.

There are a number of hypotheses about the decline of Cahokia.

One involves evidence of a defensive wall

that was built around the center of Cahokia.

So, that indicates that they had conflicts and warfare.

And there's been suggestions that maybe,

with the crowded conditions here,

perhaps there was increases in disease.

SHATNER: Did the threat of warfare or poor living conditions

cause the inhabitants of Cahokia

to abandon this thriving city?

It's hard to say.

But in recent years, another theory has emerged.

One that suggests there may have been a more sinister reason

behind Cahokia's demise.

So, one of the ideas that's been put forward is

that something quite dark took place there,

and this is why there's little evidence in the oral tradition

or the folklore of this area.

And this could be, ultimately, why the site was abandoned.

ISEMINGER: Back in the late '60s and early '70s, there was an excavation

at a small mound here on the site called Mound 72.

As we dug further into the mound,

there was a burial pit about five feet deep.

And at the bottom of that they found

53 mostly young women,

all buried at the same time,

laid out in two rows and piled in there two-deep.

Next to them were four men

with their heads and their hands cut off,

apparently in some ritual.

The burials that came out of Mound 72

quite clearly showed evidence of mass sacrifice.

We have to ask ourselves

whether this would have had any kind of impact

upon the society as a whole at Cahokia.

SHATNER: Did the vast majority of Cahokia's inhabitants

abandon their city

because its leaders were engaging in the practice

of human sacrifice?

And if so, then where did they go?

Is this tragedy enough to explain

why there is no written record

that this civilization ever existed?

For now, experts remain collectively baffled

and worry that we may never know for sure.

We really must question, you know,

what really happened, because

it could have been something much more mysterious

that we just don't know about.

SHATNER: Just off the coast of Alexandria,

in the Abu Qir Bay...

...a team of underwater archaeologists

begin the hunt for a lost Egyptian city known as Thonis.

CHRIS NAUNTON: Thonis was known

in only the sort of sparsest detail thanks to a few

ancient sources in which it's mentioned,

but it had for a very long time

not been identified archaeologically.

So we knew it must have existed because text

told us so, we just had no idea where it was.

SHATNER: Then, in the year 2000,

at a depth of some 30 feet,

divers found ancient Egyptian statues,

hoards of gold coins and jewelry, and even

the ruins of buildings and roads.

All part of the massive city of Thonis,

that was rediscovered at last.

One of the most amazing discoveries made

was the temple of Amun.

And this temple was absolutely vast,

constructed of these incredibly big stone blocks.

So, we have a really visceral idea of the size

and the monumentality of this temple.

We also have an enormous, colossal statue

of the god Hapi,

who's a kind of personification of the Nile.

It's appropriate that you would have a god like this

present at the sort of entrance,

if you like, the Mediterranean entrance

to the Nile delta region and the Nile River itself.

SHATNER: Thousands of artifacts have been recovered from Thonis,

and archaeologists estimate that it was three times

the size of the ancient Roman city of Pompeii.

But how did this vast, remarkable city

sink beneath the waves?

BRADSHAW: What we think happened with Thonis is

an earthquake in around the second century BC

caused the city to sink into the water.

And Thonis was lost to history.

But we've really only scratched the surface

in terms of what we know about the city.

A huge mystery still remains.

And in large part, that's because 95% of the city

remains underwater and remains in need of investigation.

Only five percent seems to have been discovered.

So, the questions remain.

SHATNER: While the full excavation of Thonis will take decades...

...archaeologists and explorers continue to scour the globe

in search of other lost cities

that capture people's imaginations.

The reason why people look for lost cities like

Xanadu or Petra or anywhere else

is because we want to be

the next discoverers of this

incredible lost realm that nobody has set their eyes on,

perhaps for thousands of years.

Because you just don't know exactly what

you're gonna discover.

It's exciting to think about what future

archeological finds will reveal.

Perhaps an artifact from Atlantis

will be found deep underwater.

Or the discovery of other islands like Nan Madol

will prove that the continent of Mu

once towered above the ocean waves.

And as technology evolves, lost civilizations

might be spotted without ever having to raise a shovel.

With every new revelation, we get one step closer

to understanding how our ancestors once lived.

But for now, the true history of our ancient past

will remain unexplained.

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