Original subtitles

Narrator: hierapolis.

An extraordinary roman city Built on top of mysterious,

Dazzling white formations Of rock.

This city was a pearl among

The cities of the eastern Roman empire.

Narrator: this magnificent Place hides a dark secret.

Legend says that beneath these Streets lies the gate to hell.

Narrator: why do the ancients Believe this city

Hides a portal to The underworld?

What is the deadly truth Behind this terrifying tale?

Narrator: now, Experts have rare access

To investigate this ancient Horror story

And use pioneering technology To solve

A 2,000-year-old mystery.

Narrator: In the hunt for answers,

We digitally reconstruct This spectacular roman city.

We track the footsteps of Priests and gods,

Investigate strange skeletons,

And explore a lost Sacred space to unearth

The truth about the terrifying Roman gate to hell.

♪♪

This is the ancient city of Hierapolis in western turkey.

Perched on top of stunning White cliffs

More than 500 feet high,

It's one of the most Picturesque cities

In the roman world.

Wilson: this street is The main street of the city.

Visitors would come through The north gate behind me,

Pass through the city.

They would be very impressed With all

The architecture of The buildings that were here.

Narrator: mark wilson has been Investigating the romans

For 35 years.

He explores This extraordinary city.

Hierapolis is founded by Greek settlers before

The romans take control In 133 b.C.

Wilson: after the romans Take over the city,

They begin big infrastructure Projects, building institutions

Like bath houses.

We have several theaters That are built here,

So they transformed the urban Landscape of hierapolis.

Narrator: The romans turn hierapolis into

A splendid city Of 12,000 people.

They build gymnasia And temples,

A mile long, Colonnaded street,

And one of the finest Amphitheaters

In the roman world.

But behind the grandeur lies A sinister presence,

A strange shrine to pluto,

God of the underworld And his hellhound, cerberus.

Why are they here?

Do the romans believe This magnificent city

Is home to the gate to hell?

Julian bennett investigates This 2,000-year-old mystery.

He searches for clues in An account written by the greek

Geographer strabo,

Who visits hierapolis In the first century b.C.

Strabo describes a terrifying Place believed

To be the entrance to The underworld.

[ trickling water ]

Narrator: according to strabo, This eerie place is home to

An invisible terror that Causes animals to drop dead.

Narrator: Where is this fatal grotto?

And what causes These creatures to drop dead

So dramatically?

Searching for answers, Julian explores

The area Around the main temple.

Narrator: next door to The sanctuary of apollo,

Julian finds a replica of A magnificent statue of pluto,

God of the underworld.

And beneath it, An intriguing structure.

Narrator: Julian believes this must be

The place strabo describes.

It's called the plutonium, The place of pluto.

Narrator: when archaeologists First unearth this site,

They find a carved Inscription that

Dedicates it to pluto And his queen.

Beneath it is a gateway, Just like strabo describes,

But it's blocked With stones.

Myth has it that these rocks

Conceal an entrance To the underworld,

A gateway filled with

The toxic breath of The hellhound cerberus,

Sending anyone foolish enough To enter to certain death.

Can there be any truth To this tale?

♪♪

When archaeologists remove The stones that seal

The gateway, something Mysterious happens.

Narrator: the strange deaths Explain why the ancients

Think this is The gate to hell.

But how does it work?

What is causing These sudden fatalities?

Mehmet ekmekci

First began studying Hierapolis in 1993.

He believes the bizarre Animal deaths

Must be caused by some Natural phenomenon.

Narrator: mehmet investigates The area around

The entrance to the plutonium.

In roman times, This was dry,

But now it's flooded.

Something in the water Catches his eye.

Narrator: carbon dioxide occurs Naturally in the air

And in water -- The air we breathe

Only contains a tiny amount, Just 400 parts per million.

At higher levels, It's deadly.

How much carbon dioxide Is there here?

Narrator: just 50,000 Parts per million of

Carbon dioxide, or 5%, Causes respiratory problems.

10% carbon dioxide will cause

Vomiting and loss Of consciousness.

20% can cause convulsions, Coma, and death in one minute.

After just a few seconds,

Mehmet is struggling To breathe.

Narrator: the maximum Concentration of carbon dioxide

This machine can measure

Is 100,000 parts Per million, or 10%.

In seconds,

The reading hits The top of the scale.

When the air here is measured With a higher

Specification monitor,

It's revealed to be full of The deadly gas.

Narrator: mehmet believes the Toxic levels of carbon dioxide

Explain what kills the birds And other animals.

Narrator: but it's not Only unlucky passing animals

That are caught in this Deadly trap.

Ancient texts described this Site as a place of pilgrimage,

Where worshippers come to Seek favor

From pluto and witness His power.

The priests exploit Their faith.

They sell animals to The pilgrims

And promise to sacrifice them In their name.

They walk the animals Into the enclosure,

Leading them up To the gate to hell.

Here, as if damned By the gods,

The animals fall lifeless To the ground

While the priests Magically survive.

Narrator: the discovery Of carbon dioxide

Explains the bizarre Animal deaths

And the mystery Of the gate to hell.

But there's another mystery To be solved.

If the carbon dioxide levels Are so lethal,

Why don't the priests Die, too?

Can further evidence here at The plutonium

Reveal how they escape Its deadly effects?

♪♪

Narrator: the spectacular Roman city of hierapolis,

It's said to be home to The gate to hell,

Where toxic levels Of carbon dioxide

Cause animals to Drop dead.

But why don't People die, too?

A clue may lie in the design Of the plutonium itself.

The romans build a gate Around the deadly cave.

And an enclosed arena In front of it.

Narrator: at one end is a temple Believed to house persephone,

Queen of the underworld.

On the other side,

Steps provide seating for Over 500 spectators.

The arena beneath them floods With carbon dioxide

From the cave,

Creating an invisible Kill zone,

Bringing hell to earth.

How can the audience

And the priests survive in This theater of death?

To find out, mehmet ekmekci Investigates how

The deadly gases spread Through the arena.

He takes a closer Look at

The seating area and measures The carbon dioxide levels.

Narrator: here, the carbon Dioxide levels are less

Than 10,000 parts per million, Or 1%.

Seated in the open air,

The spectators are well away From the deadly gas.

But what about the priests?

How do they go right Into the cave

And survive when the animals They are leading die?

Narrator: mehmet believes The secret to the priests'

Survival lies in the special Properties of carbon dioxide.

He uses a tower of burning Candles to test this theory.

Narrator: next, mehmet fills the Jar with pure carbon dioxide.

Narrator: The gas sinks to the bottom

And puts out the candles One by one.

Carbon dioxide Is heavier than air.

Mehmet believes This special property is what

Allows the priests to survive The deadly gas

When the animals die.

Narrator: the characteristics Of carbon dioxide

Mean the gas sits Close to the ground,

Creating a toxic cloud Around the priests' feet.

It allows them to walk in And out of the gateway

Without dying.

Do the priests believe They are

Really entering The gate to hell?

Julian bennett believes They know the deadly gas

Is dangerous.

Narrator: the priests Likely believe the deadly

Vapors rise straight from The underworld.

Narrator: but who are These secretive holy men?

An intriguing roman sculpture Could provide clues.

Narrator: attis is a tragic Figure whose story

Inspires the galli priests And a bizarre ritual.

According to legend, Attis betrays cybele when

He falls in love with Another woman.

Enraged, the goddess Drives attis mad,

And he castrates himself.

The galli priests worship Cybele by imitating attis,

Wearing long robes,

Heavy makeup, And bleaching their hair.

During a festival called The day of blood,

They hold wild parties, Whip themselves,

And some even self-castrate.

The citizens of hierapolis Are mesmerized by

The bizarre priests and their Miracles at the plutonium.

The city attracts visitors From far

And wide to witness The spectacle.

But just at the entrance to

Hierapolis lie hundreds of Solemn monuments.

What are they, and what more

Can they reveal about this Mysterious place?

♪♪

Narrator: the ancient city Of hierapolis --

At its heart is a lethal gate To hell,

Where strange priests Perform deadly rituals.

Nearby, hundreds of Stone monuments line

The road that leads out of The main gate.

What are they, And what can they

Reveal about life In this remarkable city?

Stretching for almost a mile,

It's a city of the dead,

With over 1,200 tombs -- Inside the chambers,

Archaeologists find a mass of Human remains with

Rich grave goods Like coins and jewelry.

Some tombs contain Up to 90 skeletons.

It's one of the largest

Surviving cemeteries In the roman world,

The final resting place for Tens of thousands of people.

Who is buried here?

And why is this graveyard So magnificent?

♪♪

The state of preservation And the number of tombs

Here in the cemetery Is just spectacular

And totally unexpected.

Narrator: historian mark wilson Investigates why there

Are so many lavish tombs here.

He first needs to find out Who they belong to.

A clue lies in an inscription Found on one of the tombs.

This tomb is erected by A merchant by the name of

Flavius zeuxis, And zeuxis

Is telling us, A bit boastfully,

That during his lifetime, he Made a passage around the tip

Of greece 72 times On his way to rome.

So this attests to the great Mobility of a person like

Zeuxis, who could make

So many trips like this During his lifetime.

Narrator: the inscription Suggests the tomb's owner

Works in hierapolis's Main industry.

Zeuxis is most probably A textile merchant,

Because the city was noted for Its textile production.

He's carrying his trade goods Between hierapolis and rome,

Which is 1,100 miles away.

Narrator: many of the people Buried here are

Made rich by the city's Lucrative textiles trade.

Mark believes this is Why so many

Of the tombs Still stand today.

Wilson: these tombs would take About 1 to

2 years' salary for the cost Of constructing them,

And so they invest

A lot of their resources In building

These tombs that last To this present day.

Narrator: this cemetery is So spectacular thanks to

The wealth of the city's Textile merchants.

They used the finest stone to Build magnificent tombs,

Which helps the structures Survive for two millennia.

But why is this city such

A great place to make And export cloth?

Mehmet ekmekci Investigates.

He believes the answer lies In the stunning

White rock formations On the edge of the city.

Narrator: travertine terraces Are naturally occurring

Rock formations made from Calcium carbonate.

They form when natural Spring water

Bubbles up out of the ground.

As it flows down the hillside,

It leaves behind These white deposits.

Narrator: over 400,000 years, The deposits build up

To create this Spectacular cliff

1.5 miles long and more than 500 feet high.

Mehmet believes the natural Springs that form

The travertine are key to Hierapolis's textile industry.

He investigates the water.

Fresh water Has a mineral content

Of less than 200 milligrams Per liter.

Narrator: mehmet discovers some Water here has a mineral

Content of more than 2,500 Milligrams per liter.

It's rich in Calcium carbonate,

The perfect ingredient for Fixing dye on fabric.

Narrator: thanks to this Natural resource,

Hierapolis becomes famous For its woolen fabrics,

Dyed in vibrant shades Of red and purple.

But textiles alone don't explain The wealth of hierapolis.

A ruined bath house In the city center

Reveals another clue to The city's success.

The mineral-rich waters are Channeled directly

Into hierapolis and create A thriving trade.

Ancient greeks And romans believe

The waters can cure diseases,

From asthma to eczema, And flock here to be treated.

The spa industry Makes hierapolis rich,

Helping it grow into A city of 12,000 people.

But not everyone who comes Here to be treated is cured.

Mehmet believes Some of them end up

In the magnificent tombs of The cemetery.

Narrator: mineral-rich Hot springs for textiles

And bathhouses And a cave filled

With deadly gas make Hierapolis rich and famous.

Can a strange geological Formation outside the city

Reveal what causes These bizarre natural wonders?

♪♪

Narrator: ancient hierapolis Is unlike any other roman city.

It's home to bubbling Mineral springs,

Dazzling white rock formations, And a dark cave

That spews out lethal vapors.

This trio of Geological wonders

Is evidence of subterranean Forces at work.

♪♪

Three miles deep Beneath the city

Is a huge chamber brimming With magma bubbling at almost

2,000 degrees fahrenheit.

It heats the groundwater Above so

That it leaches minerals From the rocks.

It becomes saturated with Carbon dioxide

And highly pressurized.

The immense heat And pressure try to push

The water up, But there's a thick layer

Of rock separating it From the surface.

How can it reach the cave in

The plutonium and release Its deadly gas?

Erhan altunel searches Hierapolis for clues.

Narrator: as erhan investigates, He discovers more

Mysterious damage.

A water channel has been Torn in two.

Narrator: for erhan,

There's only one Possible explanation

For what causes All this destruction.

Narrator: historical accounts Reveal that in 60 a.D.,

A huge earthquake hits Hierapolis.

It completely destroys The growing city

And two other Nearby towns.

Narrator: what causes all these Devastating earthquakes?

And can it explain the strange Gases that leak into the city?

A clue may lie in towering 40-foot-high cliffs

Just outside The city walls.

Narrator: a tectonic fault Is a fracture in the ground

That occurs when pressure Builds up in the earth's crust.

This one is called The pamukkale fault.

It's about 25 miles long.

When it moves, It creates earthquakes.

Narrator: it's this fault that Causes all the earthquakes

In hierapolis.

The city sits on a ticking Time bomb.

Narrator: erhan believes this Mighty fault is also the secret

Force that creates the mineral Springs and travertine terraces

And powers the deadly Spectacle at the plutonium.

Smaller cracks in the city Center support this theory.

Narrator: hierapolis is Built right on top

Of a tectonic fault.

It runs for a mile through

The city center and directly Under the plutonium.

Narrator: The tectonic fault explains

The phenomena seen At the plutonium.

It causes cracks That allow carbon dioxide

To escape directly Into the shrine.

It's also the force That powers

The mineral springs and creates This breathtaking landscape.

The mystery of the gate to Hell has finally been solved.

But more mysteries remain.

After an earthquake Destroys hierapolis,

In the first century a.D.,

What happens to the residents?

What can the famous oracle at

Delphi reveal about This eerie city?

Narrator: Hierapolis.

What happens to the city after

An earthquake destroys it In 60 a.D.?

Julian bennett investigates.

A first clue could lie In the city's nymphaeum,

An ornamental fountain Near the temple of apollo.

Narrator: When archaeologists unearth

The fountain's foundations, They make a surprise discovery.

Narrator: arches are a common Feature of roman architecture.

They allow engineers to span Wide gaps and construct large,

Complex structures.

But it's very unusual to find

An arch in the foundations of A building.

Narrator: experts believe that, Like many of the buildings in

Hierapolis, this structure

Is evidence that after The earthquake wreaks its

Destruction, the romans Rebuild the city.

Narrator: The ground beneath hierapolis

Is scarred by rips In the earth,

Evidence of centuries Of earthquakes.

Undeterred, the romans build Their city right on top of

These cracks, even some of Their finest buildings.

They bridge a crack Under the nymphaeum

With stone arches and build Its walls around them,

Hoping this magnificent Fountain will stand

The test of time

And provide vital drinking Water for years to come.

Narrator: julian believes the Romans know about earthquakes

And design their buildings To withstand them.

But why are they So determined to stay

In this dangerous place?

Mark wilson returns to The travertine terraces

To investigate.

The city of hierapolis

Is situated in a very Fragile but beautiful place.

And of course, Part of that fragility is

The fact that we're on A very active seismic zone.

Narrator: mark believes The travertines hold the key to

Understanding why The romans go to

So much effort to stay In a place like this.

Wilson: well, the location is Fantastic here,

Because it's situated

On one of most beautiful Natural wonders in the world.

It's also on this natural Shelf looking

Over a beautiful, rich,

Fertile valley called The lycus river valley,

And even in antiquity,

It was a very fertile Farmland that

Contributed to the richness of This city.

Narrator: the romans' Decision to live here

Isn't only a practical one.

There's also another Spiritual reason

Linked to one of

The most important shrines In the ancient world.

The legendary sacred site of Delphi in greece is

Home to a grand temple Dedicated to the god, apollo.

This is where the oracle

Of delphi makes Her famous predictions.

Deep inside the temple is A chamber where

Gas rises from a crack In the ground,

Just like in hierapolis.

The oracle priestess inhales This breath of the gods.

She enters a trance And predicts the future.

The greeks believe The fault at delphi

Is a direct channel To the gods.

They believe the same Connection exists

At hierapolis,

As the city's name Makes clear.

The greek word hieron means Holy, polis means city.

So hierapolis Means holy city,

And this is very much Connected to

These religious sanctuaries, To apollo, to pluto.

Narrator: hierapolis has an Important spiritual connection.

Here and across the ancient World, people seek out

Fault lines and geologically Active areas

To be closer to The divine powers.

The plutonium provided direct Access to the underworld,

And so the residents here Truly believed that

They were in a place Related to the gods.

Narrator: a fault crack And poisonous gases

Do not deter the later romans.

In fact, they're two of The area's main attractions.

But the power of the plutonium Does not last forever.

What can an intriguing Structure high up on

A hillside reveal about what Happens to the gate to hell?

♪♪

Narrator: The roman city of hierapolis,

Perched on top of stunning White cliffs.

Do the forces of nature That create

This incredible landscape also Cause the city's downfall?

Historian mark wilson Goes back to

The plutonium to find out How the story ends.

Wilson: today at the plutonium, We see

The entrance to the underworld Totally blocked up.

But this is not from some Natural catastrophe,

But clearly due to Human intervention.

Narrator: mark investigates Why the romans

Shut down this important Sacred site.

A clue to their dramatic Change of heart

Could lie high up On the hillside.

Here, he finds A mysterious tomb.

Wilson: among the hundreds Of tombs in the cemeteries of

Hierapolis, the question is, Why is this one special?

Well, according to tradition, On the hill behind us,

Philip the apostle Of jesus christ

Was martyred around 80 a.D., And after his death,

His body was buried In this tomb.

Narrator: according to ancient Christian texts,

Philip the apostle arrives In hierapolis around 60 a.D.

With a disciple, Bartholomew and his sister,

Mariamne.

Philip preaches The teachings of christ

And performs miracles To cure the ill.

But the temple priests, The galli,

And officials see philip As a heretic.

They arrest him, whip him, and Drag him through the streets.

They nail philip upside down On a cross to die

And hang bartholomew By the hair.

In the first century After christ,

The old gods still rule Supreme in the roman world.

In hierapolis, the galli, With their deadly rituals,

Preside over the plutonium,

And christians are persecuted For their beliefs.

But over the next 300 years,

Christianity spreads across Europe and the near east.

The emperor constantine Legalizes christianity,

And we see the beginning of Churches being constructed

Throughout these cities by The christians who live in them.

So christian religion Now becomes

The majority religion In the roman empire.

Narrator: gradually, The old gods die out.

And in the late Fourth century,

Pagan worship is Officially banned.

In the middle Of 6th century,

We see the emperor justinian Sending out a man by the name

Of john of ephesus,

And his mission is to destroy Any remaining pagan temples

And sanctuaries In places like hierapolis.

Narrator: the temple of Apollo is knocked down,

The plutonium is blocked up, And a huge church is built on

The site where philip The apostle is martyred.

Hierapolis becomes a center Of christian pilgrimage.

Wilson: pilgrims who once came To hierapolis to offer

Sacrifices to pluto at

The plutonium now come to The tomb of philip to venerate

This important apostle.

Hierapolis, once the city Of apollo and pluto,

Is now the city of philip And jesus christ.

Narrator: but the threat That comes from the fault line

Running through hierapolis Is not over.

In the 7th and 14th Centuries, two more

Huge earthquakes devastate The city.

Eventually, It's abandoned.

The seismic fault line that Caused the romans to build

The sanctuary to pluto And brought notoriety to

The city was the same seismic Fault line that eventually

Caused the destruction of The city and its abandonment.

In the end, the roman Expertise in engineering

Was no match for the forces Of nature.

Narrator: today, the ancient Gods may be cast aside,

The gate to hell closed,

But the powers that fuel it Still lie dormant

Beneath the earth until The day they may wake again.

The roman city of hierapolis, Home to a terrifying mystery,

A cave full of vapors Where animals drop dead.

But now the truth has Been unearthed.

Hierapolis sits on a crack In the ground,

A natural wonder that is The source of the city's power,

The agent of its destruction,

And the answer to the mystery Of the gate to hell.

♪♪

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