Original subtitles

Tom ward (narrates): Hidden tunnels deep underground

that helped an American city survive and prosper.

At the time,

it was the most expensive construction project

in the whole of the us.

A sunken wreck with an extraordinary past,

now reclaimed by the sea.

It's as if there's something specific

about this area which makes it lethal for shipping.

A concrete dome once intended to conceal

and protect Hitler's wonder weapons.

We have no idea how close we came to losing the war,

and this is testament to that fact.

And a mysterious building with eerie echoes of the cold war.

Massive gaping holes in the ceiling,

it looks as though something terrible

may have happened here.

Once they were some of the most advanced structures

and facilities on the planet,

at the cutting edge of design and construction.

Today, they stand abandoned, contaminated,

and sometimes deadly.

But who built them and how?

And why were they abandoned?

(Theme music)

Deep in a forest in northern France,

there's a strange concrete structure.

It's an extraordinary sight.

There's a vast concrete dome

nestling in the green farmlands.

I mean, this place is total science fiction.

Look at it. There's nothing else like it.

And this,

the shape of it is just peculiar.

Did something plug into that?

It's just a strange looking edifice, really.

What you see from outside is there's some sort of entrance...

It looks like something that you would see

maybe in a James Bond movie, some, you know, villain's lair.

(Suspenseful music)

Hidden inside, a dark, cavernous halls

carved out of the rock that lead deep underground.

Miles of tunnels stretching in every direction

disappear into the darkness.

The great steel structures

underground supporting this facility,

so something of incredible value

was happening here.

But what was it?

Nobody else had anything like this.

These guys were at least 20 years ahead of their time.

So, what is it and who built it?

And why does this building now lie in ruins?

(Explosion)

The story is rooted in Hitler's change of fortunes

during the second world war

when the Germans were suffering crushing defeats on several fronts.

As the tide started to turn against the Nazis in 1943,

Hitler turned to his great new toy box

of wunderwaffe, wonder weapons.

They wanted to do something spectacular,

something that would knock the allies

kind of back on their heels.

They were desperate for some kind of

dramatic knockout punch.

But allied bombers were doing great damage

to Hitler's industrial heartlands.

(Series of explosion)

So, he takes the decision

to move the most important ones underground

where they're build in subterranean factories.

This is one of those factories

which was built just outside pas-de-calais

in northern France.

It had to be able to withstand the intensive bombing.

This building

would have been a source of national pride.

This is the complex that was going to win them the war.

(Dramatic music)

Construction began in September 1943,

1,300 workers laboured day and night.

It was a massive undertaking...

As historian Laurent Thierry explains.

The idea was to start with the roof

to protect the underground galleries from bombings

so that they could install a launch preparation room deep down.

The galleries were to accommodate

all the required items for this site.

Garrison, power generation, and air distribution.

It was like a mini underground town,

the ultimate futuristic weapon development centre.

It was where they would build Hitler's new wonder weapon.

But what was it?

These were something that had never been seen before.

They came supersonically with no sound

and exploded in cities.

They took only five minutes from launch to impact.

This was a whole new kind of warfare.

This is la coupole

the German v-2 missile launch site.

Codenamed (speaking German).

It was built to produce

and fire long range ballistic missiles

which could hit targets more than 200 miles away.

The Germans called it their vengeance weapon,

and it was going to be Hitler's way of taking revenge

for the allied bombings of German cities.

The v-2 was the world's very first long range guided ballistic missile.

It would also become the first man-made object

to travel into space.

La coupole was the base for a weapon

that was Hitler's last hope of winning the war.

So, this is a bomb shelter for bombs.

This is 55,000 tonnes of concrete,

15 feet deep.

Just below me here

is where the rockets were to be launched.

Much of the development was top secret,

but what we do know

is that once the missiles were assembled,

they were transported out to a launch pad and fired.

The v-2 rocket was basically designed

to instil terror in the populations of anywhere it hit.

Flies high up, practically to the edge of space

and then comes screaming back down faster than the speed of sound,

no advance warning,

and it delivers this massive explosive charge.

So why did German high command decide to build the complex here?

La coupole was just 45km

from the coast of northern France

and the perfect location to attack its primary target,

London.

Hitler wanted the la coupole facility

to be able to send V2 rockets

against London at a rate of dozens a day.

This meant a site that could store hundreds of rockets

and produce them around the clock.

All of the missile components were to be stored in a vast network

of underground tunnels

before going to the very heart of the operation for assembly.

The construction zone is built on a vertical hierarchy

so that at every level, there would be specialists

adding additional elements to the V2

as it went through the construction process.

But the Germans hadn't been completely successful

in keeping la coupole's location a secret.

And in march 1944,

the first allied bombs rained down on the concrete dome.

The complex had yet to launch a single missile...

But it was already a target

for the allies' very own super weapon.

It was an earthquake bomb called tallboy.

Each tallboy bomb weighed 6 tonnes.

It was specifically designed to destroy massive hardened targets

against which conventional bombs were useless.

There would be a total of about 20 raids on the site

until July 1944.

The British would drop 3,000 tonnes of bombs onto the site

including 32 tallboy bombs during 2 operations.

One bomb landed right beside the dome

burying the entrances to two of the tunnels.

All construction was stopped, and the site was never completed.

La coupole was finally abandoned at the end of July 1944.

Today, the site is a ruin.

Andrew: We have no idea how close we came to losing the war

and this is testament to that fact.

If the German's had another year,

this would have been complete

and would have been pumping out 50 missiles a day,

don't forget the UK is 5 minutes away.

Fortunately for us, time was not on their side.

45km from Germany's capital Berlin

lies a building that looks almost palatial.

Lynette: There are so few places in Europe

that seem to still have the dust

lying on them in thick layers.

So, few places where you can see

untouched history.

It seems to be perfectly preserved until you take a closer look.

Plaster is peeling from walls.

There's an overriding air of neglect

that just permeates the place.

Mummified animals stretch out on a carpet,

their final resting place.

Their faces are a picture of death.

Everywhere there is a sense of quiet despair.

There's a theatre,

the seats are turned towards an empty stage.

And a swimming pool, which last saw water long ago.

And that's not all,

in one of the rooms,

there's a painted mural complete with Russian writing.

Andrew: There's a statue

of the former communist leader Lenin,

standing defiantly in front of the building.

But this is Germany,

what is the connection with the Soviet union?

Nearby are several smaller buildings

which are even more dilapidated.

The remaining window panes are smeared with grime,

and vegetation is growing through cracks in the floor,

and there's massive gaping holes in the ceiling.

It looks as though something terrible

may have happened here.

You have to ask yourself

what happened to the kind of power

that can create so much impact,

so recently,

and to have disappeared so completely.

Who lived in these buildings?

What were they used for?

And how were they connected to a covert spying operation

by the CIA?

For the reasons,

we need to look back to the hostility

that existed between the east and the west

during the cold war.

After the second world war,

we, the allies, were determined that we would never allow Germany

to threaten the world again.

And so, we divided Germany up and we occupied it.

That decision was made at the famous potsdam conference

which was held at the home of crown prince Wilhelm

in potsdam during the summer of 1945.

It began just nine weeks after Germany's surrender.

This was where Winston Churchill, Harry s Truman,

and Joseph Stalin met

to determine how beaten Germany should be administered.

It was decided that west Germany should be occupied

by the Americans, the British, and the French,

and east Germany by the Soviet union

which immediately began to fortify its border with the west.

Andrew: Political and ideological tensions

soon escalated between the Soviet union and the west.

And east Germany is on the fault line.

It was the iron curtain.

Because of its strategic importance,

the Soviet union needed to maintain a military presence here

in east Germany.

Firstly, to ensure there was an effective fighting force

capable of taking on NATO

and secondly to ensure

that east Germany towed the Moscow party line.

Powerful and highly mobile communist forces

in Eastern Europe

number over half a million men.

Well-trained and well-equipped,

they pose a continuing security threat

to all of Europe.

Three hundred and fifty thousand of those troops were stationed here

in east Germany.

The western group of forces as it became known

was the largest army on foreign soil.

It was equipped with the latest

of the Soviet military equipment

because if things got down and dirty

and it came to conflict,

these extremely well-equipped troops

would be the ones to confront NATO.

It's hard to imagine now,

but this was once red army headquarters.

The command and control centre

for all operations in east Germany and beyond.

But why build it here at wunsdorf,

a small town, 40km form Berlin?

The town has been associated with the military

since the late 19th century.

When the Nazis came to power,

wunsdorf was hq for the German armed forces.

And once the war ended, the red army moved in

as caretaker Jurgen naumann explains.

Military properties of the former wehrmacht

were still in superb condition.

Didn't have to build new, you just had to move in,

make some modifications,

and I guess that's why here near potsdam,

near Berlin, the high command was stationed.

According to top secret CIA reports,

it was where indoctrinated German officers would come

on political assignments...

And high-ranking Soviet officers

discuss the probability of war with the west.

But first of all,

the Soviet's had to deal with problems

a little closer to home.

There was a strike by construction workers

in east Berlin which turned into a widespread revolt

against the government.

But the Soviets couldn't allow their authority

to be undermined,

so they send in the tanks.

James: People with rocks aren't very effective against tanks

and of course the east German resistance is crushed.

Now they know they're living in a totalitarian state.

The red army was in Germany to control Germans

and confront the west.

When those Germans got out of line,

the red army did not hesitate to destroy them.

But in a military headquarters,

why are there so many non-military facilities?

It wasn't just the armed forces that lived there

but their families as well.

In the main building,

there were exhibitions, memorial rooms,

and there were small cinema rooms

where propaganda films were shown.

A lot of history about the second world war,

in particular about the glorious Soviet army.

The red army officers and their families

who served in Germany

were able to enjoy a high standard of life

that was a lot like

what they would have had back in the Soviet union but even better.

To the 75,000 men, women, and children who lived here,

it was little Moscow.

On November 9, 1989,

the Berlin wall fell,

and Germany was no longer willing

to allow an occupying army on its soil.

The huge Soviet infrastructure in east Germany

was enormously expensive to maintain

and as the Soviet state collapsed at home,

the Soviet presence in Germany had to be pulled back.

It was only a matter of time

before the Russian troops would be called back home.

And so, after a final military parade

on June 25, 1994,

the red army left for good.

Today, the former red army hq is up for sale,

but it still stands as a monument to a fallen regime.

For so many years,

Germany was about to be destroyed

by a great cataclysm,

and the scars of that on Germany

are still seen.

All over Germany, we see relics

of the enormous occupying powers

who invested so much in Germany for so long.

30km off malin head

on the northern most tip of Ireland

is a strange and confusing sight.

60m beneath the surface of the dark waters of the Atlantic

is a jumble of tangled metal.

Rob: Deep within the murky depths shapes slowly emerge...

And you start to get a sense of what's going on here.

There's a propeller, there's a hull,

there's a mass of rusty metal.

This is the grave of a sunken ship.

Dominic: Other shapes make little sense on a boat.

There appear to be guns,

tracks, turrets.

As you look more closely,

it becomes clear that these are tanks,

but there's no explanation

why tanks which should be on land are on the seabed.

What's even more surprising is that these aren't British models

but American sherman tanks.

Dozens of them,

it almost looks as though they're ready to go into battle.

The whole seabed area around there is actually a nautical graveyard.

There are ocean liners, there are submarines.

It's as if there's something specific

about this area which makes it lethal for shipping.

What happened to this ship?

Why was it carrying American tanks

and how did it end up at the bottom of the ocean?

One of the most costly campaigns of the second world war

holds the key to the reasons why.

It was the battle of the Atlantic.

Dominic: During world war two, as an island,

Great Britain was fundamentally dependant

on its allies for supplies.

The main supply line came across the Atlantic

from the United States and Canada.

In fact, it wasn't just a supply line,

it was a lifeline.

The Atlantic passage is the most important way

in which britain got its materials to defend itself during the war.

Hitler knew that one of the easiest ways

to hit the United Kingdom hard

was to cut off that all important supply route.

So, Hitler made it a priority to sink merchant shipping,

sailing across the Atlantic.

He knew that if he could starve britain

and isolate her from her allies,

he would force her out of the war.

But what connection did that have to a sunken ship

laden with American tanks lying on the seabed?

This is the wreck of the 'ss empire heritage'.

She started life as a whaler,

but she had been damaged by a mine and put out of service in 1941.

But that wasn't the end of her story.

Dominic: The 'ss empire heritage' was by no means

the cream of the merchant fleet.

But all boats were needed,

so it was patched up and put into service

between liverpool and New York.

Each time the ship made the crossing to

and from liverpool,

she had to pass malin head.

It was one of the most dangerous parts of the crossing

according to Geoff Miller

who has often dived the wreck.

Yeah, malin head can be a very treacherous stretch of water,

there's very strong tides,

and we're open to the full force of the Atlantic ocean.

Next stop off malin head is america,

which is thousands of miles away,

so with all that rough energy coming in from the ocean,

just waves, constant seas, and storms.

The 'ss empire heritage' was part of a massive convoy

of almost a hundred ships that left New York in August 1944.

It was heading towards liverpool with a heavy cargo of war supplies

including 16,000 tonnes of oil

and almost 2,000 tonnes of deck cargo

which included sherman tanks.

To counter the threat of the German u boats,

the royal Navy came up with a system of convoys,

and the idea was that up to 30 or 70 merchant ships

would sail under protective guard of royal Navy vessels.

It was almost three months after d-day

and the allies were well on their way

to winning the war.

The fighting after the landings on the beaches in normandy

was fierce.

The villers-bocage area with its fields

and hedgerows and sunken lanes

was almost tailor-made for the German defenders

and casualties among the allied infantry units were high.

But after three months of bitter combat,

the Germans were eventually forced into full retreat.

However, there was still an urgent need for supplies.

Although beachheads had been established in normandy,

what was now required was intense effort

to push all the way through France and down into Germany.

And to do that, a lot of equipment was necessary.

James: The allies cannot ship war materials,

troops, and supplies

effectively to major continental ports.

It's months after d-day that they have large,

capable ports operating under allied control.

Until virtually the end of 1944,

britain is still the great essential logistics base.

It took several days for the 'ss empire heritage'

to reach the north coast of Ireland.

She was on the home straight.

Although not complacent, there was a definite feeling

that the battle in the Atlantic was over.

In effect, it had calmed down from 1943.

And with the success of d-day,

there was a sense that shipping in the Atlantic

was freer than formerly it had been.

She was just 30km from malin head when disaster struck.

A German u boat lurking beneath the waves

had the 'ss empire heritage' in its sights.

The u boat was one of Hitler's most deadly weapons...

And this particular one was fitted with the very latest technology.

Rob: It had a snorkel

so it could stay submerged for much longer.

It hardly needed to surface, so it was very hard to spot.

It was also armed with the very latest torpedoes,

acoustic torpedoes,

which could hone in on the sound of a propeller.

Two of those torpedoes smashed into the 'ss empire heritage'.

(Explosion)

Two torpedoes might not sink a battleship

which is heavily armoured.

Merchant ships aren't armoured, it's going to sink.

This is a case

where this particular vessel got very, very unlucky.

The 'empire heritage' was carrying 16,000 tonnes of petrol,

so when the torpedo struck that,

you can imagine the fireball that would have caused,

and the sea would have been in flames.

I mean, diving in the oil filled with water,

just in flames,

must have been horrendous, must have been a horrible death.

I think it was approximately 70,000 merchant seamen

lost their lives in world war ii,

just an unimaginable horror.

When the 'ss empire heritage' went down,

over a hundred of the sailors onboard died.

And many of course were very young, even in their teens.

This was a sinking with a very real human cost.

The 'ss empire heritage' and her cargo

lay deep beneath the waves until 1995

when she was rediscovered by divers.

It's a underwater monument

to the valour of tens of thousands of merchant seamen

in world war ii

who made victory possible.

Victory would not have been possible

without all of those ships bringing in the supplies,

bringing in the men, bringing the material to britain.

Bringing the soldiers to britain,

and because of their sacrifice,

the allies win the war.

In Westchester county,

which lies 64km from New York City,

is the most extraordinary sight.

Jim: You're walking along this simple trail through the woods,

and there you see this strange stone tower...

That's round, doesn't have any doors or windows.

It's very mysterious.

I mean, who built it? What's it doing here?

What's it connected to?

These brick monoliths scarred by graffiti

dominate the landscape

as if they are guarding a long-lost secret.

And that's not all.

There's a rectangular stone structure

that seems completely out of place in this urban setting.

If you went inside, you'd see wheels,

you'd see levers, you'd even see what looks like a bit of a gate

which is operated by pulleys.

But they're rusted and they're corroded,

so you can tell by looking at it

that they haven't been used in a long time.

Hidden beneath is something more eerie...

It's a tunnel partially filled with water

that seems to be unfinished.

You see that the tunnels

aren't brick-lined all the way up around.

In many instances, they're just almost like half-lined

and then as you look above,

you can see that it's just the raw rock...

Almost like they'd left it like it as it was excavating.

This tunnel stretches into the darkness

and seems to go on forever.

But where does it go?

At the end of the tunnel, there's a clue.

Water thunders down this stepped slope,

and above it,

this imposing steel arch that stretches right across a gorge.

But how are all these things connected?

In the early 19th century,

New York City was facing several problems.

Even back then, New York was already the biggest city

in the United States

and its business and economic hub.

The problem that you have with new world cities like New York,

cities that spring up

and then rapidly develop is that very quickly,

they use the local water system around them,

the streams and the rivers that are there.

We need water to live,

and if you can't supply that, that's a major problem.

As the population of New York increased rapidly,

the water supply became polluted and diseases began to spread.

One was cholera,

and an epidemic ravaged the city in 1832.

The disease struck fear into the hearts of new yorkers.

It seemed to attack randomly and at frightening speed.

Apparently healthy people would leave their houses

in the morning, contract the disease,

and be dead by nightfall.

More than half of those infected did not survive.

These diseases were a huge concern for people

even in very sophisticated,

rich urban areas like London or New York.

Epidemics would spread and they were absolutely terrifying.

And disease wasn't the only problem,

3 years after the cholera epidemic,

a great fire destroyed almost 700 buildings

which lay at the very heart of the city's commercial centre.

Buildings were made of wood, they were very close together,

so if one house caught on fire, boom,

half your city is up in flames in minutes.

So, New York needed water and lots of it.

The question was,

where would the vast quantities it required come from?

And how would they get it into the city?

The local authorities decided to build an aqueduct.

And if they pulled it off,

it would be one of the most spectacular feats

of engineering ever seen.

The plan was to damn the croton river,

some 64km north of Manhattan and build a channel

to bring that water into the city.

It was one of the most ambitious construction projects

ever attempted.

The old croton aqueduct was a mega project.

And to get this channel of water all the way into Manhattan

was really aggressive for the technology of the day.

So, how would it work?

The aqueduct would use the earth's gravity

to move the water from the reservoir to the city

along a gradual gradient or slope...

And the challenge for its builders was to maintain this gradual slope

across a variety of terrain.

You've got to go over valleys,

you've got to go through hills,

through rock,

and all the way from source to the delivery point,

you have to maintain or very close to that gradient.

Not only that,

the aqueduct had to be built in sections

along its entire route.

Each one, like this bridge,

was a major engineering project in itself.

If these sections didn't connect properly,

the water wouldn't be able to reach the city.

Writer and broadcaster,

Jim meigs explains the challenges its builders faced.

The aqueduct was really built by hand,

by human and animal muscle power.

Everything had to be excavated by hand,

hauled away by animals,

and ultimately,

constructed to carry all this water without any modern equipment.

But in some places, they had to get through a hill

and that meant tunnelling through solid rock,

and that's what we see in this section here.

They came in with hand drills that they would drive into the rock.

You can actually see the tracks of the old drill bits

in a couple of spots here.

Then they would stuff those holes with black powder,

blow them off and that would fracture the rock.

This was incredibly difficult, dangerous work.

There was the threat of cave-ins,

they were operating with explosive black powder,

there were all kinds of things that could go wrong.

The engineers were also worried about a build-up of toxic air

within the aqueduct

that might contaminate the water supply.

So, they built ventilation shafts into the tunnel.

There are 21 of these still standing.

These serve a number of purposes.

First of all,

they allow air to circulate through the tunnels

so you don't get pressure build up in key parts of the system.

They also allowed the water to aerate in some way,

it keeps the water fresh if you will,

but they also served as access points,

so every third or fourth ventilation shaft

was also used as an access point into the tunnel system.

But construction was beset by problems.

In early 1841, part of the dam collapsed,

the valley was flooded, and 3 people were killed.

Then its mainly Irish workforce went on strike in protest

at their wages being cut.

Jim: You have to remember when this project was being built,

everything was done by hand labour.

They required an army of labourers, many of them Irish,

who laboured in this absolutely,

you know, brutal task for several years

to get this huge piece of engineering completed.

When the aqueduct crossed a valley,

the workers had to move

thousands of tons of soil and rock in handcarts

in order to build an embankment to protect it.

And at its base,

they built a culvert as mavis Cain

from friends of old croton, explains.

And it was built to protect the aqueduct

from the thrust of water

from the many, many streams and rivers

that there are in Westchester.

So, the culvert serves as a way of keeping the water

from weakening the stones of the aqueduct.

Wherever there is a stream strong enough to cause damage,

there is a culvert.

The aqueduct took 5 years to build

and cost the then enormous sum of $13 million.

And at the time,

it was the most expensive construction project

in the whole of the us.

So, would the various sections join together

and allow the water to flow those 64 long kilometres

to New York?

On June 22, 1842,

they were going to find out.

Jim: The aqueduct was an absolute overnight immediate success.

Without the aqueduct,

they wouldn't have been able to expand the city the way they did.

So, I'm standing right in the main channel

of the aqueduct, this is where the water flowed.

On a normal day, it might be up to my knees

or maybe up to my waist.

And behind me, you can see this big iron gate

that they would use to close off the flow

if they ever needed to empty the lower portions of the aqueduct.

If the aqueduct was such a success,

why was it abandoned?

By the early 1880s,

some 40 years after it was completed,

the aqueduct was no longer able to meet the city's needs.

In a sense, the aqueduct was a victim of its own success.

It was such a boon to the city

that it allowed New York to continue growing

at this dramatic pace,

and the population of the city was going up.

Pretty soon, they were using up all the water

from the old croton aqueduct.

In 1885,

they began to build a new aqueduct on top of the old dam and reservoir.

To save it from being forgotten forever,

the old croton aqueduct is now preserved.

A unique part of New York's remarkable industrial heritage.

Dougal: You can see some of the hidden gems

that are there,

the chimneys, the air ventilation systems.

As nature overgrows

and as we don't follow these paths very often,

then they'll become more and more hidden.

(Instrumental music)

Now, they lie abandoned,

but once,

they were at the cutting edge of engineering.

There are echoes from history in these decaying structures.

They remind us of terror and war

but also of great innovation and human endeavour.

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