Original subtitles

WILLIAM SHATNER: A vast empire that mysteriously collapsed.

An ancient metropolis

reclaimed by the jungle.

And an abandoned city that sits

in the middle of the desert.

All over the world, we're surrounded by the ruins

and artifacts of ancient empires

that were once thriving, powerful cultures.

What's left behind offers intriguing clues

about how our ancestors lived.

And it makes you wonder how an entire civilization

can simply disappear.

As we dig deeper,

what secrets will be uncovered

about mankind's past?

Well...

that is what we'll try and find out.

♪ ♪

SHATNER: Explorers John Lloyd Stephens

and Frederick Catherwood mount an expedition to investigate

reports of mysterious ruins

located in this remote, largely uncharted region.

After scouting and mapping

miles of dark, impenetrable jungle, they find

some unusual features in the dense brush.

Oddly shaped stones,

peculiar carvings,

and strange artifacts that could only be...

man-made.

It isn't long before they realize

they've made an incredible discovery:

the remains of the mysterious

ancient Maya civilization,

deep in the rainforest.

CARL WENDT: And what was so remarkable to Stephens and Catherwood

is eventually they found temples and platforms and pyramids.

There was monumental architecture and conical mounds

and other building platforms in the rainforest.

And to look at these cities in the jungle,

kind of coming out of the jungle, was...

was just absolutely remarkable.

And it got people's attention.

SHATNER: On their return to the United States,

Stephens and Catherwood publish an illustrated book

of their findings,

detailing 44 individual ruins.

Readers are astounded by the book's

meticulous illustrations,

which portray a sophisticated ancient society.

And news of the astonishing find

quickly spreads around the world.

WENDT: The Maya become more mysterious as we collect more information.

They have a sophisticated writing system.

They obviously have a sophisticated religious system.

And calendar system.

And so the calendar, which would've been a very useful tool

for the Maya elite and priests to be able to understand,

say, for example, when there was gonna be a solar eclipse.

They were ancient astronomers and architects.

They have social structure

that we're just beginning to understand,

and their cities are remarkable.

SHATNER: At its peak,

the Maya civilization stretched from Guatemala and Belize

to western Honduras and El Salvador.

Their total population was estimated to be in the millions,

and concentrated in large city centers like Copán,

Tikal and Calakmul.

And then, suddenly, during the ninth century AD,

this advanced society just... collapsed.

Vast cities, ornate palaces, towering pyramids,

all of it, completely abandoned,

left to be reclaimed by the jungle.

But why?

ED BARNHART: The mystery of why

Maya civilization collapsed is one

that archeology has been debating forever.

830 is right about when all of the cities in the Maya area,

and all over Mesoamerica, are falling apart.

They drop their tools, and they walk away.

They're abandoning those cities, and it's a mystery.

Where did the people go? Why did they leave?

If you have such a sophisticated civilization,

how do these things collapse?

What went wrong?

SHATNER: For decades, archaeologists have speculated

as to what might have caused the sudden demise of the Maya.

Dozens of theories- blaming everything

from drought to disease to devastating earthquakes-

have been proposed.

Yet, the simple truth is,

no one knows what really happened.

But a recent study, using state-of-the-art technology,

might have provided a significant clue.

An airplane operated by the University of Houston's

National Center for Airborne Laser Mapping

flies 2,000 feet above the thick jungle canopy.

As the plane reaches its target area,

an advanced scanning technology called "lidar" is used

to fire laser pulses through the trees at the ground below.

When the resulting data is later compiled

into a three-dimensional rendering of the area,

the scientists are stunned by what they see.

Once lidar got involved,

we saw the roads leading out into other city centers.

We saw thousands upon thousands of houses.

Collectively, all the areas that they covered

were over 60,000 new buildings that we didn't see before.

Previously, they thought

that the Maya reached probably a maximum level

of population of around five million,

but the estimates now take us

up to at least 15 to 20 million.

SHATNER: Ever since the rediscovery of Maya ruins

by Europeans in the 19th century,

nearly every piece of data uncovered

about the Maya raised more and more questions.

But now, after scientists began using lidar,

they finally started to find answers,

such as the possible cause

of the Maya civilization's collapse:

war.

WENDT: Once we started going out

and recording and mapping these sites,

we see defense warfare structures.

This is a remarkable thing, that we never knew

that these defensive works were out there,

leading archeologists to scratch their heads

and basically say, "Oh, my gosh, the Maya were warlike,

and warfare was very important."

DAVID WHITEHEAD: We know there was warfare going on.

They were building all kinds of defensive structures.

Could that have something to do

with the vanishing of the Mayans?

BARNHART: More and more,

as the classic period went on,

monuments became full of war imagery,

and people taking captives

and people being beheaded.

So we know war was a factor.

If it was just war,

the victors would've claimed the land,

and the losers would have beat it.

But that's not the fact.

Everybody left. Why?

SHATNER: According to the Popol Vuh-

the written history of the Maya-

they believed that time was cyclical in nature.

Each cycle lasted for a fixed number of years,

at which time, a great cataclysm would wipe the slate clean

so a new world could be born from the old one's ashes.

So was this the real reason?

Did the Maya abandon their great cities

and disband their culture simply because an ancient prophecy

told them when exactly to do it?

BARNHART: The timing is very interesting.

In 830, a great cycle is ending,

and there was certainly evidence for them

to believe that things were going bad.

There were climate problems,

there were resource problems,

there were people fighting.

Were they timing the leaving of their cities

to the calendar that they created?

That's a... a big possibility.

SHATNER: Right or wrong, the Maya believed

that the end of their civilization was at hand.

And while that may seem like a far-fetched notion,

there actually exists one group of people

that hold similar beliefs:

the descendants of the Maya.

When you talk to modern Maya people

in the Guatemalan Highlands,

people called daykeepers, ajq'ij,

they are priests who still

follow the calendar, and they teach people

that things begin, and they come to an end.

And that to be in harmony

with the world you need to know these cycles

and change before the world changes you.

It's very possible that, back then,

when all the signs that the world was going...

a serious wrong direction,

that the Maya civilization as a whole said,

"These are the signs. The time is now.

Let's collectively change ourselves."

SHATNER: Was the collapse of the Maya civilization

simply the result of a self-fulfilling prophecy?

It seems that the truth about their fate

may be a matter of belief.

Which may also be the case regarding

an ancient society in Cambodia that mysteriously abandoned

one of the largest temple complexes ever built.

SHATNER: Deep in the northwestern jungles

of this small nation,

tucked between Vietnam and Thailand,

sits the abandoned ruins of Angkor Wat,

a massive, ancient complex of temples.

Experts believe that Angkor Wat is the largest

religious structure ever built.

STEAVU: It's just a massive, impressive sight.

swallowed up by the jungle.

Trees are wrapping around some of the stones

and sculptures that-that remain,

yet you can still make out some of the exquisite sculptures

between leaves and branches.

And you can see something really majestic underneath.

BARNHART: Angkor Wat is huge.

When you walk up to its front entrance,

it's a bridge going across the moat, and then,

a causeway going to the temples themselves.

And they're so far off in the distance,

you walk across that bridge for ten minutes,

and you're still not at the temple.

SHATNER: All told,

Angkor Wat encompasses more than 401 acres

of buildings, temples and gardens,

and a 700-foot-tall spire sits

at the center of the complex.

Angkor Wat was built in the 12th century AD

by the Khmer people,

and it was the spiritual center of their empire.

DOUGHERTY: It's difficult to explain

just how important this place was.

In fact, "Angkor Wat" means "capital city"

or "capital temple," or "city temple,"

depending how you translate it.

So, this was not only a religious center,

it was also a political center,

it was a military center.

There was absolutely no separation

between religion and daily life.

The temple served all of these purposes.

And it was home to tens of thousands of ordinary people

who were farmers, merchants

living in this tremendously important religious center.

STEAVU: It was a massive, vibrant city.

The urban landscape extended

far beyond Angkor Wat itself, in every direction,

for, uh, miles,

so there were anywhere between about 750,000

to a million people living around the city of Angkor.

SHATNER: In the year 1431 AD,

the Khmer people abandoned Angkor Wat.

For decades, archaeologists have speculated

as to what caused the demise of the city.

Numerous theories, blaming everything

from climate change to invading armies, have been proposed.

And yet, no one knows for certain

why nearly a million people

chose to abandon these magnificent temples.

DOUGHERTY: The abandonment of Angkor Wat

illustrates to us that something catastrophic had occurred

within Khmer society.

This incredible place

was still capable of supporting large numbers of people,

it was still an important temple,

but it was almost completely abandoned.

It was just left.

And what that suggests is that

something changed in the Khmer people.

SHATNER: Some experts have proposed

that because Angkor Wat was such an important religious site,

it may have been abandoned for spiritual reasons.

DOUGHERTY: Angkor Wat

was the link between mortal people and the gods.

And it was built by Suryavarman II,

who fought a series of military campaigns to unify his people,

brought stability, prosperity.

And Suryavarman II intended

Angkor Wat to be his mausoleum.

STEAVU: The tomb of Suryavarman II was intended

to be located underneath the central tower.

And there's a hole at the top of the central tower

that lets in a beam of light.

And that beam of light would have shone directly

onto the tomb, demonstrating in a way

that Suryavarman was directly linked to the divine.

DOUGHERTY: Suryavarman II

clearly intended to be buried at Angkor Wat.

He would be interred in the central temple.

But he died on a military campaign in what is now Vietnam,

and nobody knows what happened to the body.

SHATNER: Curiously, after King Suryavarman died,

and his body was not placed in its intended tomb,

the living conditions in Angkor Wat took a turn for the worse.

There were repeated droughts in the region,

which led to famine,

because there was not enough water for crops.

But on the other hand, there were also huge monsoons

that, at times, would cause major flooding.

Some scholars believe

that these calamities may have been seen

by the Khmer people as a sign

that their connection to the gods had been lost,

and that it was time for them to abandon Angkor Wat.

DOUGHERTY: The Khmer people

would have remembered the time of Suryavarman II,

of this golden age that had existed.

But later, things weren't as good.

Could it be that the link

between mortals and their god had been broken?

(birds singing)

STEAVU: If what made Angkor City great

was the blessings that were sent down from the gods,

then when things started going more badly for the city,

people would naturally interpret

that the gods again are taking away their blessings.

And then that, in turn, would serve as a cue

for the Khmer people to also leave behind the city.

BARHART: All civilizations on the planet,

no matter how big they are,

they eventually fall, and Angkor was no different.

And the factors were not just as simple as one thing.

There were a number of things happening.

In many regards, the abandonment of Angkor

was just an acknowledgement

that however large and grand their life was there,

that the gods didn't favor it, and it was time to end it.

SHATNER: Did the Khmer people abandon Angkor Wat

because they believed

that they had fallen out of favor with the gods?

It's an intriguing theory,

but not all ancient cities are mysteriously deserted.

Some are frozen in time,

like a town located near Mount Vesuvius

that was engulfed in a deadly cloud of volcanic ash.

SHATNER: At approximately 1:00 p.m.

on a peaceful, late summer day,

this ancient Roman city in the shadow of Mount Vesuvius

is shaken by a massive volcanic eruption.

Within minutes, superheated gas and lava

engulf the city and its surroundings.

(people screaming)

In an instant, thousands of people

are buried alive as a city

that was once their home...

suddenly becomes their tomb.

Nearly 2,000 years after the eruption,

Pompeii is a city that remains frozen in time.

LAPATIN: This eruption was

what we call a pyroclastic eruption,

where clouds of ash and debris

hundreds of degrees hot came flowing down the mountain,

flash-frying everything in its path.

And, miraculously, the heat of this cloud

was enough to carbonize and preserve,

rather than destroy, all kinds of information.

We have well-preserved architecture,

wood and organic materials, foodstuffs,

human remains,

animal remains that have been preserved for 2,000 years

beneath this volcanic debris.

SHATNER: Today, the excavated ruins of Pompeii

offer archaeologists and tourists

a breathtaking look at the doomed ancient city.

Perhaps the most intriguing discovery found beneath the ash

from Mount Vesuvius's eruption

was an ancient Roman structure located not far from Pompeii,

known as the Villa dei Papiri.

LAPATIN: The Villa dei Papiri

was a Roman luxury villa

that was full of sculpture

and marble and bronze.

The villa was discovered by chance

in 1750 by well-diggers,

who, tunneling about 75 feet through volcanic debris,

first hit a colored marble floor with an amazing pattern

made up of bright red and yellow marbles.

We think this was once the vacation home

of a Roman senator of the highest rank

of an old noble family, named Lucius Calpurnius Piso.

SHATNER: The volcanic ash that buried Villa dei Papiri

did not only preserve the physical structure.

It also entombed a library

that contained more than 1,800 papyrus scrolls.

These scrolls are an extraordinary record

of the thoughts and writings of people who lived

nearly 2,000 years ago.

SEALES: Those texts were discovered

when the city was excavated,

and some of the artifacts were first found.

The people who discovered them didn't know what they were.

They thought that maybe they were pieces of branches or logs,

because they were rolled up and carbonized.

Until someone finally realized these are texts on papyrus.

LAPATIN: The Villa dei Papiri library is significant because

it's the only surviving library

from antiquity with its contents.

There were scrolls found

that date to the third, second and first century BC,

and the first century AD.

About 300 of them or so have been un-scrolled,

and they contain mostly philosophic texts,

some poetry, some literary criticism,

a little bit of history.

But many of the scrolls are so tightly bound together

and carbonized that there's been a moratorium

on attempts to open them.

SHATNER: Fear of damaging the scrolls has left many of them

virtually untouched for over 100 years.

But new technology has presented a potential opportunity

to read these mysterious ancient texts.

Scientists in the Computer Science Department

at the University of Kentucky have developed a new method,

known as "virtual unwrapping,"

which uses a sophisticated X-ray machine

to scan the scrolls without damaging them.

SEALES: The virtual unwrapping that we innovated

basically allows a 360-degree set of views

to be collected from an object

that rotates in front of an X-ray beam.

This is a real scroll that's 2,000 years old,

and in cross section, we can see there's damage,

there are parts that are missing,

sections that are broken.

Now we're using our software for the second step,

which is to trace these wraps all the way through

so that we can build a 3D model that lets us

flatten that out and then read the text that's on it.

And once we're done, we've achieved this image

that's on the left, which is the final,

completely unwrapped version.

This is a quote from Democritus,

who was an early Greek philosopher,

and is very well known for having postulated, with others

that materials are made of atoms.

I think it's remarkable that 2,000 years ago,

Greek philosophers were postulating

what we now know is true from science.

SHATNER: Thus far, the team has been able

to digitally scan two complete scrolls,

and a number of fragments.

They hope that, in the future, technology will advance

and allow them to reveal even more.

But what secrets might be contained

in those 2,000-year-old scrolls?

One exciting possibility that has been suggested is

that original letters written by Jesus's apostle Paul

could have been kept within the library of Villa dei Papiri.

RIC RADER: The Villa of the Papiri was entombed

about 40 to 50 years after the death of Jesus.

At this time, the original apostles are now out

doing their mission work in various parts

of the Mediterranean.

So, it's entirely likely that the Villa of the Papiri

could have a collection of copies of Paul's letters.

SEALES: If the letters from the Apostle Paul circulated

and found its way into the collection,

such a discovery would represent the earliest Christian material

that we have, almost dating back

to the time of Christ and the disciples.

Being able to use these techniques

to understand history in a way that's almost forensic

is gonna bring surprising things forward,

and we're gonna be revealing more secrets

than we'd ever imagined before.

Are there even greater secrets contained

within the papyrus scrolls of Pompeii?

Hopefully, archaeologists will soon find out.

But some mysteries of ancient civilizations are not buried

beneath volcanic ash but rather

hiding in plain sight.

For instance, there's a vast pyramid mound,

constructed more than a thousand years ago,

that is located in the heartland of the United States.

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 stands the ruins

of an ancient, man-made pyramid mound

that was built centuries ago,

and is as tall as a ten-story building.

BILL ISEMINGER: 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.

COLLINS: 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 that 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, 40,000-50,000 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.

And 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, 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.

COLLINS: The burials that

came out of Mound 72

quite clearly showed evidence of mass sacrifice.

And 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: While we may never know the true fate

of the inhabitants of Cahokia,

it's quite remarkable that parts of this vast complex

can still be seen today.

But not all ancient ruins

are hiding in plain sight.

There's a city, located in the Arabian desert,

that was not merely abandoned

but rather deliberately concealed.

SHATNER: Swiss explorer and geographer

Johann Ludwig Burckhardt sets off on an incredible journey

across the desert to uncover the secrets of the Middle East.

Johann Ludwig Burckhardt was

quite an extraordinary character.

Um, he traveled throughout Syria, Jordan, Palestine,

and eventually into Egypt.

He also practiced the Islamic faith.

And the reason for this was that

he didn't want to be seen

as a Western treasure hunter.

SHATNER: During his travels, Burckhardt heard rumors

of a mysterious ancient city known as Petra

that was hidden somewhere in the deserts of Jordan.

For centuries, the exact location of Petra

was kept secret from foreigners.

But Johann Burckhardt was determined to see Petra

with his own eyes,

and so he hatched a wild plan.

PARADISE: The area had always shown conflict,

it had always shown a certain amount of hostility

to European visitors.

And so Burckhardt spent months in the region,

learning the local dialect of Arabic,

and then perfected a bedouin outfit

to look like a local, or something close.

The disguise was needed to get him in the door.

SHATNER: After spending months following clues

in search of the city,

Burckhardt traveled through a dark, narrow desert canyon,

and to his astonishment,

stumbled upon the stunning ruins of Petra,

which were even more impressive than he had imagined.

Burckhardt was the first European to lay eyes on Petra

in more than 500 years, and his vivid account of the city

made headlines around the world.

Suddenly, the world reads about Petra.

The entrance into Petra

is this magnificent carved structure

about 140 feet high.

And it was carved, it was hewn directly out of the rock.

And that's the beginning.

Petra was a large, large city of 30,000 to 50,000 people

that was thriving between

about 500 BC and about 500 AD.

It had a city center, it had a main street,

it had everything you would think of, even to this day,

that a large city would have.

The builders of Petra were the Nabataeans.

They were a culture in their own right

who adopted the art and architecture

of the Greek Hellenic world,

the Greco-Roman world,

but also had influences from Assyria

in what is today Iraq.

And they blended all of this together to create

the incredible carved architecture

that you see at Petra.

SHATNER: The more than 800 carved structures at Petra

are so iconic that in 2007, the site was named one of

the New Seven Wonders of the World.

Ever since Petra was revealed in 1812,

historians have wondered

what could have caused the collapse

of such a prosperous city?

For decades, it was thought that shifting

trade routes were responsible,

but research conducted by archaeologist Thomas Paradise

has revealed new information regarding the downfall of Petra.

We're really fortunate that we keep

putting pieces of the puzzle together.

Using archaeological excavation,

using GIS and laser technology,

we're starting to put these pieces together

to understand Petra.

New research is indicating that a large flood hit

in the fifth century that wiped out the downtown

for at least a year or so.

The city rebuilds after that flood,

but it marks the beginning of the decline from its golden age.

SHATNER: The re-discovery of Petra has revealed

that the city was important, not just historically,

but also spiritually.

Because, as it turns out,

this ancient city has a connection to the Bible.

PARADISE: Up above Petra-

and it's visible from most parts of Petra-

is a mountain called Jebel Haroun.

Jebel Haroun means the Mountain of Aaron.

And we do know legend says

that's where Moses's brother Aaron is buried,

below a large tomb on the top of the mountain.

The keeper of the holy site at Jebel Haroun...

over the years, I-I came to know his family.

So, he invited us up there to go into the building itself,

and then to climb into the tomb.

That gets you excited because you realize you're part

of a tradition from 3,000 years of pilgrimage.

Petra's been called the Lost City of Stone because

here we see a city of 30,000 to 50,000 people

that slowly fades from the history books over time.

And what we're going to find out about Petra

in the future is probably more incredible

than what we already have uncovered.

SHATNER: The re-discovery of Petra is an extraordinary find

of both spiritual and archaeological significance,

and one that rewrites the history books.

But sometimes, the most remarkable secrets

about ancient civilizations can be found

by studying not only the ruins

but rather the DNA of the people who built them.

SHATNER; Here, on the vast green pasture of Salisbury Plain,

stands perhaps the most storied wonder of the ancient world:

Stonehenge.

First constructed around 3100 BC,

these imposing sarsen and bluestone monoliths were rebuilt

and repositioned a number of times

over the next 1500 years,

eventually settling into the current configuration.

But today, almost 5,000 years after its creation,

Stonehenge's original purpose

remains shrouded in mystery.

TIMOTHY DARVILL: Stonehenge is a complicated monument.

It's a very long-lived monument.

We're always changing

our interpretations of Stonehenge.

And this is in large measure because

these societies don't seem to have had writing.

They haven't written anything down

that's come down to us, at least.

So, we're having to piece together our understanding

of the monument from what we have

in the archaeological record in the monument itself.

SHATNER: For centuries, researchers assumed that

the ancient people who constructed Stonehenge

were native to the British Isles.

That could be changing.

Because thanks to modern genetic technology,

researchers have been able to conduct DNA testing

on Stone Age skeletons that were recovered

in the area around Stonehenge.

And the results suggested that Stonehenge's builders

weren't native to ancient Britain at all.

They may have arrived from much, much farther away.

COLLINS: It was generally thought

that Stonehenge must have been built by the local people.

But new DNA evidence suggests

that the builders of Stonehenge had come

from distant Anatolia,

modern-day Turkey.

NEWMAN: DNA analysis that shows this migration

from Turkey to Ancient Britain is very, very interesting.

Because what we're finding here

is this direct connection over a very long period,

starting with sites such as Göbekli Tepe,

which was in Southeast Turkey.

Then we have similar stone structures, like stone circles

or stone avenues in Portugal, along the Iberian Coast.

Then we have the sites in Brittany, France,

which again date to this very early phase.

And then we start seeing the megalithic constructions

of ancient Britain.

So, this DNA analysis shows that

they were bringing this megalithic knowledge.

And this has now been proved through DNA research

from Turkey, through Europe,

into ancient Britain.

SHATNER: Is it possible that Stonehenge was constructed

by the same ancient people from Turkey

that built other massive stone monuments all over Europe,

as newly discovered DNA evidence suggests?

It's one of many intriguing theories

about ancient engineering that has been brought to light

by modern technology.

New technologies are certainly gonna open up

a whole series of new questions.

And it's going to answer a few things

that we didn't know too much about.

So, there's still a lot of work to be done in figuring out

some of the secrets of ancient times.

I don't know how they moved such large stones

those great distances, or why they did it.

Why, particularly, was that the location

for the stones to be extracted,

and this the location to actually build them?

It doesn't make sense to me as an engineer.

I would always want to move those stones

the shortest possible distance

to the site that I'm gonna build from.

We've wondered since the day we discovered it

how they did it, and we still don't know.

Whether it's sprawling cities that were suddenly abandoned,

curious artifacts that may hold clues about the past,

or even the physical remains of our ancestors,

human history has left behind fascinating mysteries

that we're still trying to understand.

Perhaps one day modern technology will shed

new light on ancient civilizations,

but until then, their secrets will remain...

...unexplained.

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