Original subtitles

NARRATOR: A mysterious mound hides many secrets.

- Traces of ancient civilisations that go all the way back

to the Bronze Age.

NARRATOR: A prehistoric stone circle rises from a watery grave.

- It's one of the oldest structures made by humans anywhere on Earth.

NARRATOR: Declassified satellite photos

that could be linked to history's greatest general.

- This is truly an exciting discovery.

NARRATOR: And strange shapes reign atop a mountain

in the land of gods and monsters

- What we're looking at may just solve a mystery

thousands of years in the making.

NARRATOR: Everywhere we look on our planet,

there's evidence of the past...

in nature...

in buildings...

in relics.

Each holds a mystery that technology now allows us to see from above.

What new secrets are revealed?

- (beeping)

- (gentle music plays)

NARRATOR: It's believed modern humans have lived on Earth

for as long as 300,000 years...

creating complex civilisations that have left behind

many ancient mysteries that can only be solved with a view from above.

Lying on the northern outskirts of the European continent,

the rugged landscape of Norway features immense mountains

and a coastline carved by deep glacial fjords.

And on the low-lying plain of Vikiletta,

a view from above captures an odd and startling sight.

- In southern Norway, there's this huge mound

on an otherwise totally flat field.

- It's nothing like the craggy mountains

you see in the rest of the country.

The one thing that really stands out is this lump or hill

that's in the middle of it all.

It seems rather out of place.

- Is it a natural formation or human-made?

And what's it doing here, right next to a highway?

NARRATOR: The strange hill is roughly 80 metres across

and stands approximately 13 metres high.

- Imagine running the length of a football field.

That's how long it would take to get across this thing.

- So what is this thing?

- When I really look at this mound, it kind of reminds me of a drumlin.

NARRATOR: Drumlins formed during the last ice age

approximately 10,000 years ago, as glaciers acted like enormous,

icy bulldozers, carrying and depositing

rock and soil sediment as they shifted and moved.

- When glaciers retreat, they sometimes leave behind

a landform that's essentially an area of elongated hills

aligned parallel to the flow of ice.

- The movement of glaciers results in most drumlins being long

and tapered in appearance.

But our mound in southern Norway is round,

so it's not likely to be a drumlin.

NARRATOR: So, if this mound wasn't carved-out

by a massive glacier thousands of years ago, just what is it?

Perhaps a view from above, roughly 100km to the north,

can help.

Here, a similar circular hill stands.

Known as Rakni's Mound, it is the largest

burial mound in Scandinavia.

- Norway's landscape is littered with ancient burial mounds.

It was, for centuries, a customary means to honour

and dispatch the dead.

NARRATOR: Could this be what we're seeing

in this sheltered plain in southern Norway?

In 1968, archaeologist Erling Johansen

and his team, dig a trench in the mound to try and unlock its secrets.

- Johansen discovers alternating layers of soil,

stone and turf that confirm that this is a human-made structure.

- The team also find burned human bones.

- Cremation was common in ancient Norway.

- So this is definitely a burial mound.

- They were built for important members of the community,

who'd be buried with everything they believed that they needed

in the afterlife.

That could be weapons, furniture, jewellery and even animals.

- The community would build them over the remains of the departed,

creating a very noticeable, sacred gathering place.

NARRATOR: But Johansen and his team soon discover

much is missing in this mound.

- Besides the bones, all they found was a single amber pearl.

- This is supposed to be the final resting place

of a big deal member of the community.

So where are all the fancy grave goods

that should be here?

- We need to find out when this burial mound was built,

because that could tell us who built it

and who they built it for.

NARRATOR: Historical records reveal that the mound

is called Jellhaugen... or 'Jell Mound'.

- The story goes that it was built for King Jell.

- Two questions: who is this guy?

And why does he have such an enormous burial mound?

- Unfortunately, the King Jell trail goes cold in a hurry.

There's no hard evidence that he existed.

- But the site is a burial mound.

- The tradition of burial mounds ends at least 1,200 years ago,

and to build a mound that size back then

could take a hundred men a whole year.

- In Norway, who's got the manpower, strength and tenacity

for something like that?

- I'd say Vikings.

- Vikings. - Vikings.

NARRATOR: The Vikings were renowned seafaring people from Scandinavia,

part raiders, pirates, traders, explorers and settlers.

And Vikings were also famous for building things...

including a burial mound or two.

Perhaps a Viking burial mound almost 200km away

near Vinje Fjord can provide a clue.

- Next to Norway's Vinje Fjord,

archaeologists found a Viking-era cemetery

with evidence of more than a dozen burial mounds.

- These fjords were full of Vikings.

They go to sea, they plunder, they come back.

- They die and they're buried.

- And in terms of grave goods, burials at Vinje Fjord

do show evidence of important community members: Viking chiefs.

NARRATOR: Could it be that Jell Mound

is the final resting place of a once important Viking leader?

- Carbon dating pins the building of Jell Mound

to between the fifth and sixth centuries,

around 1,500 years ago.

- Traditionally, the Viking era is placed

between the ninth and the twelfth centuries.

- Jell Mound appears to have been built

before the age of Vikings even began,

so it was built by someone else.

NARRATOR: In 2017, construction work on the field adjacent to Jell Mound

prompted the consultation of archaeologists

from the Norwegian Institute for Cultural Heritage Research.

- They decide that instead of physically disturbing

what might be more historical finds around the Jell Mound,

they'll use ground-penetrating radar to map the entire field.

- It's like having X-ray vision to see what's under the soil.

- It's exciting to think about what else could be under there.

- Turns out there's a lot.

NARRATOR: The Geo-radar view from above,

reveals the presence of more archaeological features

undetectable to the human eye.

- Looking at these LiDAR images, it's almost like peeling away

different layers and it actually deepens the mystery.

NARRATOR: The presence of so many buried structures

indicates that this location was once of great importance.

One discovery in particular intrigues archaeologists.

A bizarre shape that just might be the crucial key

to solving the mystery.

- What the hell is it, and why is it in a burial mound?

- They find this elongated structure.

It's 19 metres long and 5 metres wide.

- Given where this is located in Scandinavia,

I immediately wonder if that's a Viking boat.

- I knew it. Scratch the surface in Norway and you find the Vikings.

- But the site is 2kms from the sea.

What is any kind of boat doing here?

NARRATOR: Perhaps a look at the Viking pre-christian

pagan beliefs can offer some insight into why a boat is here?

- In Norse mythology, burying a boat with the deceased

was believed to provide safe passage to the next world.

- We know Vikings followed this tradition

because other boat burials have been found in Norway.

NARRATOR: In 1879, a Viking ship was discovered

in the Gokstad burial mound near Sandefjord.

- And inside it, excavators found a male human skeleton

surrounded by everything he'd need in the afterlife;

the bones of his dogs, a peacock, horses and riding equipment.

- Talk about an important member of society.

NARRATOR: The presence of the Viking Longship

indicates the burial of a high-status person,

but why here?

Perhaps a clue lies in the fact that the boat is not alone.

To date, archaeologists have found 13 different sites

in the field surrounding Jell Mound.

From fire pits that mark the earliest traces

of human activity, to longhouses signalling centuries

of habitation to Jell Mound itself

and finally, the buried Viking longship.

In all, features that span almost 4,000 years of human history.

- In just this one farmer's field,

there's evidence of not only centuries,

but millennia of human activity!

- Traces of ancient civilisations that go all the way back

to the Bronze Age.

- And recent discoveries near Jell Mound

show that this has been a burial site for a very long time.

- The question is why?

- The combination of ceremonial buildings

and burial mounds seems to mark the Jell Mound field

as an ancient "central place".

We know of this tradition from contemporary sites elsewhere,

but this is the first time a central place

has been found in this area.

- So they were more common than we knew.

- When sacred burial spots survive through so many eras,

it's usually evidence of power struggles.

The winners lay claim to the area

by burying their dead in the same place.

- With all the waterways near Jell Field,

all that opportunity for trading and raiding,

it makes sense as a location for power struggles.

- The only artefact found here from the Viking era is the boat,

which puts the Vikings squarely in that tradition

of conflict resolved by moving into someone else's burial spot.

- And since Jell Mound was built before the Viking era,

it's a crucial link in a tradition that was already well underway,

- whoever was buried there.

- So we can thank the odd appearance of Jell Mound from above

for bringing our attention to an ancient civilisation

in this corner of Norway.

- And who knows what else they might find

in Jell Mound Field in the future.

NARRATOR: From ancient secrets buried

in a remote Norwegian field

to a mystery that has seemingly come out of nowhere,

a view from above reveals another strange sight

that could change our understanding of human history.

Almost 2,500kms south,

perched on the shore of Spain's Tagus River,

a strange formation suddenly appears.

- It's located right at the edge of the Tagus River.

On the water side, there's this strange opening.

- It's an odd sight.

From the sky it looks like a letter 'C'

with a grouping of items inside.

- As we get closer, we see that it's a collection of standing stones.

Many are six feet tall.

- It's not a random arrangement.

It's clearly purposeful.

- What exactly are we seeing here?

What could it be?

NARRATOR: Archaeologists note its uncanny resemblance

to so-called 'stone circles', ancient megaliths.

The most famous of which is found in Wiltshire, England,

known as Stonehenge.

- The best evidence suggests that Stonehenge was constructed

between 2,000 and 3,000 BCE,

making it four to five thousand years old.

- This is when our ancestors begin to build complex structures,

this crucial time when we're starting

to become settled in communities

rather than just being hunter-gatherers,

stone circles arrive at an important bridge in our history.

NARRATOR: And in Britain, the view from above reveals

hundreds of these megalithic monuments

scattered across the landscape that over the centuries

have had experts debating the exact nature of their origin and purpose.

- Even though they've been widely studied,

they're still pretty mysterious.

Some say they were places of ceremony.

Others believe they were used for astronomical

or solar measurements.

NARRATOR: Was this stone circle in Spain

built for a similar purpose?

Could it have been an important ceremonial site

or an ancient solar calendar?

- Many ancient structures were designed to face

the rising or setting sun, such as the pyramids

built by the Maya at Chichen Itza.

- Stonehenge also was designed with this in mind,

and crowds still gather there on summer and winter solstices

to see the sunrise light up its carefully placed standing stones.

NARRATOR: Perhaps the view from above will provide

another piece to the puzzle.

The apparent opening near the water's edge

forms what looks like a corridor and faces east,

the direction of the rising sun.

- The way stone circle is oriented makes the best case yet

for it being a place of important ceremony.

NARRATOR: Given the comparison to the famous henge in England,

this mysterious stone circle has come to be known

as "Spanish Stonehenge."

But historians call it the 'Dolmen of Guadalperal',

'Dolmen', being the term for a megalithic tomb.

- Stone circles are often ancient burial grounds.

Human remains have been found not only under Stonehenge,

but many other stone circles.

NARRATOR: Is this what we're seeing in Spain?

The location of an ancient tomb or burial ground?

Etched into one of the larger stones, a possible clue.

- Some believe that carvings on the stone represent a serpent.

- Serpent carvings were widely associated with immortality

because snakes shed their skin and live on,

perfect for a burial site.

NARRATOR: And it's believed that the builders orientated

the entrance to align with the summer solstice

to allow sunlight to shine through the corridor and illuminate

the inner sanctum.

- You can just imagine the dramatic impact of this once-a-year visit.

NARRATOR: Yet when researchers surveyed the site,

they found no evidence of human remains.

And there's another peculiar aspect to this site.

A recent view from above, shows the stone circle isn't even there.

- It doesn't appear in satellite images from the year before,

but in 2022, "poof", it's suddenly there.

Why?

- One of the effects of climate change is severe drought,

and in 2022, we see it happening all over the globe.

- 2022 saw Europe's worst drought in 500 years.

NARRATOR: And the record-setting drought brought the Tagus River

to an alarming low level, revealing ancient mysteries

that had been kept hidden under water.

- Climate change does have this weird silver lining.

Sometimes it offers us an opportunity

to learn things about the past.

NARRATOR: But the sudden appearance of this megalithic structure

raises another strange question.

- What was it doing underwater in the first place?

- How did this incredibly important site end up completely underwater?

NARRATOR: Perhaps a nearby view from above

will provide answers.

Just 300kms to the northwest, the same drought reveals

another haunting site.

- At the Spanish-Portuguese border, the ghost town

that was once called Aceredo is suddenly visible.

NARRATOR: A ghost town, because residents

were forced to evacuate in 1992 when the area

was flooded to accommodate the Alto Lindoso Reservoir.

Spain is a country of reservoirs, and of over 1,200 large dams,

more than any country in the European Union,

thanks, in part, to former Spanish Dictator Francisco Franco.

- Shockingly, Spanish Stonehenge was submerged on purpose.

NARRATOR: As part of his plan to modernise Spain,

Franco launched massive civil engineering projects,

including the damming of the Tagus River.

- Franco completed the dam in 1964, creating the Valdecanas Reservoir.

It brought irrigation to the region but flooded Spanish Stonehenge.

NARRATOR: Prior to Franco's intentional flooding,

the historic site sat above water.

In fact, in the mid-1920s, it was studied

by German anthropologist Hugo Obermaier.

- Tools found by Obermaier include flint knives, axes,

grinding stones from the community that built the monuments.

Pottery and ceramics were also found,

so these were settled people.

- Some of the artefacts could date Spanish Stonehenge

to 7,000 years ago, making it one of the oldest structures

made by humans anywhere on Earth.

NARRATOR: Not only may this stone circle be older than many

of its counterparts in Britain, there's another key difference.

- When it was built, it was a completely covered enclosure.

KAREN: The clue is that huge mound and all the pebbles

that on first glance looked like a letter 'C'.

They are what remains of the original enclosure.

It's an extremely impressive feat

of engineering from the ancient past.

NARRATOR: And while the exact function of this

'Dolmen of Guadalperal' is hotly debated,

a closer look has sparked new ideas.

- Some believe that the carving on the huge stone isn't a snake

but actually a map of the nearby Tagus River.

If true, this would make it one of the earliest maps

ever to be discovered in Europe.

NARRATOR: But a map to what?

It's unclear what significance the river might have held

for the builders of this ancient stone circle.

- All these historically significant possibilities

make Spanish Stonehenge an extraordinary site.

- So we need to protect it, and other sites like it.

Tourists are now discovering Spanish Stonehenge,

and damage is a real concern.

- It's survived a lot, from intentional drowning

at the hands of Franco to rebirth from climate change drought

caused by the rest of us.

- Without a view from above, we might never have noticed it.

NARRATOR: From a mystery stretching back to the stone age

to another from the dawn of human civilisation,

the view from above uncovers hidden truths of our ancient past.

Almost 4,400kms to the east in Iraq, and over 60 years in the past,

an ancient mystery reveals itself.

- OK, this is quite strange,

because you've got what looks like an almost perfect square

and it's kind of etched in this field in the middle of nowhere.

- This is definitely something man-made.

- Looking at the square, I'm wondering who decided to build this,

and how long has this been there?

NARRATOR: in 1960, American spy satellites passing over

the Darband-i Rania pass in Iraqi Kurdistan

snapped images of a ghostly square outline in a remote farmer's field.

- And it's not a different kind of grain,

because we see some of the same colours

extending beyond the square shape.

NARRATOR: The odd sight measures roughly 150 square metres.

In many places this could be brushed off as nothing,

but not here, in arguably one of the most historic places on Earth.

- OK, what could this be?

And why is it here?

NARRATOR: Often called the "Cradle of Civilisation,"

Iraq was home to ancient Mesopotamian peoples

who developed the world's first writing, agriculture and cities,

between 10,000 and 3,000 BCE.

- With this region's crucial historical importance,

I want to know what is happening with this bizarre square-like shape?

NARRATOR: Easier said than done.

The history of this region is a complex and bloody saga,

rife with centuries of conflict as powerful civilisations

sought to control it-a struggle that continues today.

- From the Iran-Iraq war to the U.S. invasion,

from Saddam Hussein to ISIS, this is a volatile spot.

- It's not until decades later when hundreds of thousands of photos

are declassified that archaeologist Jessica Giraud

discovers this mysterious square.

- But with conflicts on the ground in the 1990s,

archaeologists are stymied for a few more decades

and questions surrounding the origin of the square go unanswered.

NARRATOR: It's not until 2016, when archaeologist

John MacGinnis and his team travel to northern Iraq

to investigate what's behind this mysterious square shape.

- So it's one thing to be at our desks in the British Museum

analysing satellite imagery, but you can't stop there.

You have to go to the field

and see what the site actually looks like

and seeing whether there really is archaeology there or not.

NARRATOR: Once on the ground, the team discovers that the square

is in fact, the footprint of an ancient man-made structure.

But what was it?

- Maybe something similar in shape and close by can offer a clue?

NARRATOR: Just under 6kms to the south

along the Euphrates River, in what was once the Sumarian city

of Ur, stands one of the best-preserved examples

of ancient buildings of comparable shape and size.

The ziggurat.

- Ziggurats are found across Iraq and Iran

and had both religious and administrative functions.

NARRATOR: Ziggurats are symbolic buildings

dating back thousands of years that were found in the major cities

of Mesopotamia, including the ancient civilisations

of Sumer, Babylonia, and Assyria.

Could this be what we're seeing at Darband-i Rania pass?

- But ziggurats are usually rectangular, and our square is not.

- Even square ziggurats are solid buildings,

so if this is where one used to stand, what we should be looking at

is actually a solid square.

- And what's curious about what we see in the crop field

is that it's not solid.

It's an outline.

- Maybe that's the key to discovering its identity.

- So you've got to ask,

what else around here could produce a square outline just like this?

NARRATOR: Perhaps the answer lies

with a relatively more recent civilisation.

One whose imperial power spanned the western world.

KAREN: The Roman Empire conquered lands

from Europe to the Middle East, North Africa and Western Asia.

- Including Mesopotamia and now Iraq.

- The Romans built square forts across their empire,

like the one we still today in Gonio, Georgia.

And in Roman-ruled Turkey, they built a square walkway

around the market.

- So 2,000 years ago, the Romans are in Iraq at the same time

as they are building square outlined structures.

And in an Iraqi crop field, we've got an unexplained square.

- When we take a closer look at the square outline,

we discover that it's actually being formed by something

that is not there; an area where the local crop is barely growing

or not at all.

- Could the crops' inability to grow there be a sign

that there's something hidden just beneath the surface,

perhaps something like walls?

NARRATOR: That's exactly what a team of archaeologists,

led by Dr John MacGinnis from the British Museum want to find out.

- The first feature which really stood out

was a substantial wall about five to six metres thick.

So that immediately told us we had a fort here.

So since time in memorial, this location on the pass

would've been a strategic control point for all traffic going through.

- Controlling those access routes put you

in a very powerful position indeed.

NARRATOR: This part of the world has been at the crossroads

of empires for millennia- from the Sumerian,

Babylonian,

Persian,

Greek, Parthian,

Roman,

Ottoman and British-just to name a few.

Is this small square in rural Iraq

a remnant of a fort from one of these former empires?

- From our first on-the-ground inspection,

it was immediately clear that this was not just the site of a fort,

but of something much bigger.

NARRATOR: Using drone photography

and magnetometry to further map the site,

John's team uncovers something truly amazing.

NARRATOR: The single square in the old black and white photograph

reveals itself to be just the tip of the iceberg.

- What we found was a network of streets and buildings coming off it.

We have the large fort 150 metre square.

We have a smaller square building in the southeast of the site.

We have some indication of domestic buildings.

- So this could've been a city.

- A settled city.

- It was so exciting from working from the satellite image,

then inspecting the site on the ground to realise

we had discovered a city.

This was a lost city.

- Iraq is the cradle of civilisation.

It's where the oldest cities began.

So if there's this previously unknown city from a major empire

suddenly being found here, that is big news.

NARRATOR: Has MacGinnis and his team discovered

the ruins of a long lost city?

And if so, whose city is it?

In the hope of answering this question,

the team turns their attention to a nearby unidentified mound.

- Perhaps the most obvious feature to investigate

was a huge stone mound in the southern corner of the site.

- And jackpot!

- It rapidly became clear that this stone mound

was not a random accumulation of stones,

but contained the remains of a very substantial building.

- It's a huge building that hasn't been seen in over 2,000 years!

- So what is it?

- It's a huge building, 23 metres square,

built out of stones, the walls originally standing

maybe eight metres high,

it was brightly and colourfully painted.

So it's pretty likely it's the site of what we think is the manor

of the governor of the city.

- But when was it built, and by whom?

NARRATOR: With the hope of answering these questions,

MacGinnis and his team continue the excavation

of this ancient estate, seeking artefacts that will unveil

the identity of this unknown city.

- We'd only found one piece of sculpture,

but that was incredibly exciting.

The fact that it was a marble, and also the fact

that that part of the statue was not wearing clothes

immediately suggested this was Hellenistic sculpture.

- Meaning Greek? Not Roman?

- A fairly well-known Greek passed through here.

- He was undefeated in his entire military career.

That's probably why they added "Great" to his name.

- Alexander the Great.

- He conquered lands all the way to India,

spreading Greek culture throughout the known world.

- It's not that I'm jealous, but he did it all before he was 30.

- We know from the written sources that Alexander the Great

founded a large number of cities across the territory

that he founded.

Some still bear the name Alexandria or Alexandretta.

Other cities we know existed but they haven't been found.

NARRATOR: The size of the city at Qalatga Darband is huge,

estimated at approximately 70 hectares,

worthy of Alexander's name.

- That's the equivalent of 70 rugby fields.

This is a big, new, old city.

NARRATOR: News of the discovery makes headlines around the world

and the media pose a very tantalising question:

have archaeologists discovered a lost city

of the legendary Greek conqueror - Alexander the Great?

Dr John MacGinnis and his team are wary of such claims

as they continue their search for clues that may solve this mystery

of the city's identity.

- We have multiple evidence for Hellenistic influence.

We have the statuary from the monumental building,

we have column bases, which are in the Corinthian Greek style.

The monumental building was roofed with terracotta tiles,

and last but not least, we have the evidence

for olive oil production.

This is not the norm in the region.

It's very much the result of Greek influence.

The pottery which was found in the excavations

dates to what we call the early Parthian period

roughly 150 BC to around the time of Christ.

Secondly, the sculpture that we found, that's been dated to, again,

exactly this period.

So the city itself is from a slightly later time period

than Alexander himself.

NARRATOR: Alexander died in 323 BCE, at least a century

before the artefacts found in Qalatga Darband

were created, leaving the team with only one conclusion.

- Qalatga Darband is not one of the lost cities of Alexander.

- So who lived in the big house?

- Can we date the manor house to determine

who its residence could be?

- We think at the moment it was occupied

for around 100 or maybe 150 years,

starting sometime in the middle, second century B.C.

And then going on till around the time of Christ.

As we now know, this relates to the expansion

of the Parthian Empire.

That was one of the great empires of antiquity.

- The Parthians aren't as well-known as the Greeks and Romans,

but they were a major empire in ancient Iran.

- Since we know less about the Parthians

than the Greeks and Romans, finding this site

could be even more important than finding a lost city of Alexander!

- We do know the impact of Hellenism was substantial

and that the Parthian elite had a great love of adopting elements

of Hellenistic culture.

NARRATOR: So if the founding civilisation of this ancient city

remains lost in time, what clues remain to tell us of its fate?

- We do know that the area, the monumental building

was destroyed in a catastrophic fire.

This is evidenced by thick layers of ash

which cover every room in the building.

- The evidence does point to a fire, and if that's true,

what could have caused it?

- One possibility is Roman campaigns,

and particularly we know there was a campaign of Mark Anthony

in 36 B.C. in this general region.

- So the Romans didn't build a fort here as we initially guessed,

but they may have destroyed what others established.

- As human conflict goes round and round.

- What a historic find.

And all because of an unexplained shape

in a far-off field spotted with a decade's old view from above.

NARRATOR: From a lost city hidden in the cradle of civilisation

to a mystery perched high in the birthplace of democracy,

a view from above uncovers what might be the most intriguing link

to our ancient past yet.

On the southern tip of the Greek island of Evia

is the small coastal town of Karystos,

where an ancient mystery is uncovered on the nearby slopes

of Mount Ochi.

- This aerial footage captures a surreal image,

what looks like these massive cylinders

on the edge of a sheer cliff.

- What are they doing here?

There's nothing else around, just this huge pile

of what look like a logjam.

- They appear to be perfectly formed.

Almost too perfect.

Are they human-made?

- Or are they the result of some kind of natural occurrence?

Like an earthquake or some other geological phenomena?

- We are here in the cradle

of one the most ancient human civilisations.

The cradle of Greek mythology with its mythic creatures and gods.

- Do these strange objects

have anything to do with any of that?

- From far above, these cylinders look a lot like felled trees

that you would find in a forest.

- Which makes sense since Mount Ochi was once covered

in great forests of chestnut trees.

NARRATOR: Today, what's left of these ancient woods

can only be found on the high eastern slope

of the mountain: an area known as Kastanolongos.

- It's estimated that Kastanolongos has existed for thousands of years,

since prehistoric times.

Which means it's one of the last

remaining ancient forests in the world.

- We know that, in terms of firewood,

these forests were used in Ancient Greece as a vital source of energy,

but they were also used as building materials.

- I wonder if there's any chance that these could be abandoned logs

from ancient chestnut trees, left over

from age-old logging activities.

- They look like logs, except when you take a closer look

at these piles from the air, they don't really look like wood.

Could these be made of stone?

NARRATOR: An answer might be found on the other side of the world

in the Petrified Forest National Park in the Badlands

of northeastern Arizona.

- If you can believe it, this used to be a lush forest

some 225 million years ago.

But what you're looking at now is a fossil of that forest.

- Over that long period, the wood from the forest became petrified.

- Which means what we're looking at is a forest

that's been turned to stone.

NARRATOR: Is that the case here on the Greek island of Evia?

Could this be an ancient forest that has also turned to stone?

- From a few hundred feet up, they appear grey

or brown in colour, which is consistent

with what we know about petrified wood.

- But there are a few critical details that appear to derail

the petrified wood theory.

For one thing, these cylinders aren't buried,

which is necessary for wood to become fossilised.

- For another, if these are indeed trees,

they would have markings left over from where branches were cut off.

These don't have that.

- One of the hallmarks of petrified wood

is that it's usually embedded with caches of semi-precious stones

of varying colours.

- But a closer look shows that they don't contain

any crystal stones.

- What we're looking at is not petrified wood.

NARRATOR: Could these mysterious objects in fact be stone?

Can their shape offer a clue?

- On closer inspection, they appear to be perfectly

formed stone columns.

NARRATOR: Very much like those found here in eastern California,

a US national monument known as

the Devil's Postpile.

- They certainly have the look of the cylinders in Greece.

- What we know about these cylindrical columns

is that they're made of basalt and are perfectly fitted together

like a mosaic.

- But we've got one big problem,

because when scientists conducted radiometric dating

on these pillars in California, they found that they were actually

created 100,000 years ago by lava flow.

NARRATOR: But there has not been any volcanic activity

on Evia for millions of years.

- Unlike the geological wonder that is the Devils Postpile,

the same natural forces don't appear to have occurred here.

Something else has to explain what we're seeing.

NARRATOR: So if these pillars aren't the product of natural processes

could they be man-made?

- Could the columns be leftover building materials like those

used in complex Greek architecture?

- Did this drone accidentally discover the ancient ruins

of an undiscovered temple here on Evia?

NARRATOR: Other than these stone columns,

there's no evidence of other materials or structures

that point to such a grand building.

- But could they have been dumped here for some reason?

Could the temple they belonged to be somewhere else on this island?

NARRATOR: Not far away, at the foothills of Mount Ochi,

a possible answer: a Byzantine castle

known as Castello Rosso.

- Were the mysterious columns uncovered at the edge of the cliff

once a part of this magnificent building?

- It's a medieval fortress that was built between 1209 and 1216.

And over a period of nearly 500 years,

it changed hands from the Greeks, to the Franks, to the Venetians,

to the Turks, and back to the Greeks.

- But there's a major issue with the theory

that these strange columns might have once been

part of this fortress.

- It's called Castello Rosso for a reason:

its stones are reddish in colour.

- And these columns on Mount Ochi have this grey-brown colour to them

so that doesn't fit.

NARRATOR: But just a few kilometres to the north,

another ancient structure looms,

one as curious as the pillars themselves;

the dragon house, said to have been built by mythical Greek monsters!

- This mystery just got a lot more interesting.

And really, how can you have a story about Ancient Greece

and not include a mythical creature or two?

- (roaring)

- Well that would certainly explain how the stone columns

wound up here on the side of that cliff.

They were carried off and dropped here by dragons!

- Archaeologists and historians have been puzzled over this

drakospito building for generations, unable to determine who built it.

- Its construction is highly unusual.

It doesn't have a foundation.

And while it's built with massive stone blocks,

no mortar was used.

- Whoever built the drakospito had to hoist heavy slabs

two metres above the ground at an altitude of 1,400 metres.

Hard work.

- So, whoever did that had to be incredibly powerful.

- Thus the legend that it was built by dragons.

- Archaeologists and historians have also puzzled

over drakospito's exact purpose.

- It's been placed in a location that gave whoever lived there

an unobstructed 360-degree view of the entire area.

- Which has led some to conclude

that it's an ancient astronomical observatory.

NARRATOR: But a view from above throws a wrench in that theory.

There isn't just one dragon house on this island, there are roughly 25.

- Surely they're not gonna build 25 astronomical observatories

in such close proximity to one another.

- So what was their real purpose?

- In 1959, an excavation of the dragon houses

uncovered pottery and broken pieces of ceramic

on which they found some writing.

- So it wasn't dragons that lived there.

It was people.

- But who were these people and did they have anything to do

with the mysterious columns that were revealed from the air?

NARRATOR: A clue lies in one of mythology's greatest heroes,

in whose honour it's believed, these dragon houses were built.

Hercules.

- Hercules is known as the patron of quarrymen.

And there's this legend that states that all these huts were built

so that Hercules could watch the quarry workers from afar

and give them this courage and strength to continue their work

in the quarries.

- Which means there was a quarry here on Mount Ochi.

- OK, so the Hercules angle is a bit of a stretch,

but it is believable to think that the dragon houses

were once the residences for local workers

at the quarry on Mount Ochi.

- Would knowing what they were quarrying help us understand

why the columns were abandoned?

NARRATOR: A closer look reveals that they're made

from a unique type of marble known as Cipollino.

- This Cipollino Marble,

which is very specific to the area

in and around where our mysterious columns were discovered,

was extremely popular in Rome.

- But this is a Greek island.

How did the Romans get their hands on rare Greek marble?

It's not like they were friendly neighbours.

- In fact, there were several brutal military clashes

between the Roman Republic and various Greek states.

- One of those was the Battle of Actium in 31 BCE,

where Octavian Caesar famously defeated Cleopatra,

the Greek Queen of Egypt, after which Greece fell

under Roman occupation.

- During Roman occupation,

most of the marble from Evia was exported in large monolith columns

and used in such classical structures as the Domus Augustana

and the famed Hadrian's Library.

- The Cipollino Marble columns on Evia

are actually evidence that this island

was once home to a massive quarry, run by one of the most powerful

civilisations on Earth.

The mighty Roman Empire.

NARRATOR: But what happened to this massively successful

Roman quarry?

Why were these columns abandoned?

- A clue might be in how they've been left here.

They're not exactly piled neatly.

In fact, quite the opposite.

- it's kinda like these weird columns were just dumped suddenly

as though the workers were in this huge rush to just get out of there.

NARRATOR: Was it an earthquake or another natural disaster?

- The age of these columns suggests that they were abandoned

roughly in the 3rd century A.D.,

which coincides with one of the greatest events in history.

The decline of the Roman Empire.

- Perhaps a military alert lead to the sudden withdrawal

of the Romans from this area and the ceasing of the quarrying activities.

- In 2019, a company contracted to build windfarms on Evia,

made an incredible discovery.

They found evidence of not one but three

previously undiscovered quarry sites,

Anatoli, Trikorfo, and Trikorfo II.

- Actually, it turns out that the discovery of these columns

was only the tip of a very big iceberg.

- This unique view from above really has shined a light

on a rare slice of history and kinda brought it back to life.

- These massive columns abandoned for millennia

are a brilliant reminder of the ancient world

and its power, ingenuity, and beauty.

- These columns are rock-hard remnants

of two great ancient civilisations.

And they serve as powerful reminders of the remarkable achievements

of those who came before us.

And what better way to admire them, than with a view from above.

NARRATOR: From monumental burial mounds in the land of Valhalla,

to a resurfaced cryptic megalith

to a lost city nestled in the cradle of civilisation

and a long-forgotten mountaintop of stone

that bore the weight of empires,

the view from above helps unlock mysteries

of our ancient past.

Subtitles by Sky Access Services