All language subtitles for Secret.Nazi.Bases.S01E05.Bergkristal.The.Atomic.Threat.1080p.AMZN.WEB-DL.DDP5.1.H.264-BurCyg_track3_[eng]

- This was a city underground.

- [Narrator] Five miles
of tunnels buried 80 feet

below a small town in Austria.

- There's an interesting
mystery here.

- It must have been housing
something very secret.

- [Narrator] Here, in
1944, the Nazis set out

to build Hitler's
newest wonder weapon.

- Nobody could imagine
such a ferocious weapon.

- Leaps and bounds ahead of
what the Allies were using.

- [Narrator] Decades
later, historians wonder

if there was more buried here.

- What's there, what's
Hitler got to hide?

- Some terrible things were
happening in these tunnels.

- [Narrator] And an Austrian
filmmaker's discovery

leads to new questions.

- The Nazi really
hid it very well.

- [Narrator] But officials
claim there's nothing there.

- Their sources have shut down
any further investigations.

- Is the truth too
dangerous to tell?

[dramatic instrumental music]

[tranquil string music]

- [Narrator] St.
Georgen, Austria,

a little town just east of Linz,

the idyllic setting
hides the dark truth

of one of the largest and

most mysterious underground
compounds in the Nazi Empire.

- We love mysteries
and conspiracies.

so the minute we see the
entrance to these tunnels

we can't help but
want to walk in

and find out a little bit more.

- Whenever you see a
tunnel of this size,

this deep, underground,

it's almost inescapable you
don't think what was happening.

And there's gotta be a secret.

- It's difficult to build.

It's a lot of effort, a lot
of work, a lot of planning.

And that's interesting, I wanna
know why did they do that.

- [Narrator] What
secrets are buried

beneath these quiet hills?

- It's really amazing.

Some big structures!

Wow!

[urgent instrumental music]

- [Narrator] Bergkristall
or Rock Crystal

is a grid of tunnels
covering an area

of more than 530,000 square
feet, 80 feet underground.

The original system was
nearly five miles of tunnels.

But due to fear of
collapse the majority

of the system was filled in

with concrete in
the early 2000s.

There's now only about
a mile of tunnel open.

But the tunnels of
Bergkristall may only be part

of a larger mystery.

Austrian filmmaker
Andreas Sulzer

has been researching the tunnels
and the surrounding area.

- We have to cut
this route to get in

with the heavy equipment.

And it took us a
while to get in here.

It's my job as an
investigative journalist

to do a good research and
I think I'm not alone.

I'm part of an
international group

with very experienced
historians and military experts.

- [Narrator] Andreas
has uncovered evidence

he claims points
to something more.

- [Andreas] And they
put a lot of effort

to hide it carefully.

- [Narrator] Government
officials think otherwise.

- I offered them to make

an international
research consortium.

They always refused.

Why, what's the reason?

What's the problem to work
with experts, internationally?

There must have been something
more than officially known.

- All governments have a duty
to protect their citizens,

and sometimes that means
withholding information.

So, the question is here.

Are we talking about a situation

in which authorities believe

that the truth is too important

or too dangerous to tell?

[urgent string music]

- [Narrator]
Bergkristall is the only

officially acknowledged
tunnel system in the area.

- I can't imagine
building a tunnel

of that size underground,
and as quickly as they did,

and reinforcing it as much.

- [Narrator] The Germans
hired Viennese engineer

Karl Emil Franz Fiebinger
to design Bergkristall.

- The nature of this
ground lent itself

to very efficient tunneling.

They didn't need a
tunneling shield,

which is a complex
piece of machinery.

They didn't need to
blast their way through.

And so, they were able to
make fairly quick progress.

- It's pretty astounding.

There's constraints
here that we don't have

when we're working
on the surface.

You can only fit so many
workers in one space.

You can only operate so
much machinery in one space.

- Whilst these tunnels
may have been dug quickly,

they were designed
and built well.

They were designed to last.

- [Narrator] Fiebinger was known

for his underground engineering.

And after the war was
brought to America

as part of Operation Paperclip.

- Operation Paperclip by the
Allies prioritized grabbing

as many Nazi scientists,
engineers, technology,

and systems as possible,

and whisking them back
to the United States.

- [Narrator] What
could've been the purpose

of such a vast network of
tunnels so far underground?

- With these tunnels there
are so many questions

as soon as you look at it

that just beg to be asked?

- It must have been housing
something, something big.

Probably extremely dangerous.

Something that you wanted to
keep very, very well hidden.

- We do know that
diabolical military research

was being done in the tunnels.

- So, Bergkristall would be a

very juicy target
to hit, indeed,

if you knew where it was.

- [Narrator] Andreas believes
there's more to this place

than what's in the
official records.

He made a surprising discovery

while investigating a
former SS Rifle Range.

- Yeah, here it is, you see?

Is it here?
- Yeah.

Oh yeah, here's the next one.

So, this here was the
original soil level.

And we had to cut through
with the Caterpillar.

And for our surprise, here,

we found hard steel

and it's a tank barrier out
of steel, those crosses.

So, this is a very
important find,

because on a normal rifle range

you never would have in the
middle of the shooting line

a tank barrier.

This was the first hint
that here must be something

in the deeper ground.

- There must be more here.

- [Narrator] A tank barrier
would only be installed

to keep invaders out.

What were the Nazis
trying to secure here?

And why did authorities cover
it up with tons of soil?

- You see the level?

The ground level here is
higher than the level here.

- And the Nazis hid it very
well putting all this soil.

So, you can imagine
how much work this is

to fill up this soil
in here to hide it.

It's unbelievable.

- Andreas is not just digging

into the earth of these tunnels.

He's also digging into
the accepted history

as we understand it, of
the Second World War.

[tense instrumental music]

Austria is incredibly important
to Germany in World War II.

For Hitler, it was a sign of
his divinity that he was born

on the exact border
between the two countries.

It meant that annexing that
country, taking it over,

making it integral to his Reich
was a part of his destiny.

- There were Nazis
within Austria

that were trying to
overthrow the government,

push the government to
welcome the Germans.

And, finally, on March
12th, 1938, it happens.

Austria is annexed.

And Hitler gobbles up Austria

basically without
a shot being fired.

Austria offers the German people

not only territory next to
Germany but natural resources,

it's a natural resource-rich
country, and skilled labor.

Some of the leading scientists
at the time were Austrian.

[unsettling string music]

- [Narrator] Following
the annexation of Austria,

slave labor was brought in

to build Mauthausen
Concentration Camp.

The camp was located near a
granite quarry 12 miles east

of the city of Linz.

And, today, is one of the
most visited by tourists.

- All the concentration camps
were unimaginably horrific,

but Mauthausen was
one of the worst.

It was one of the first.

It was one of the largest.

And it was one of
the most deadly.

Mauthausen had tens of
thousands of prisoners in it.

We don't have an accurate count

of how many died in Mauthausen,

but the numbers that
are given are anywhere

from 125,000 to,
perhaps, 320,000.

Mauthausen had people
from all over Europe.

There were Jews there.

There were soldiers.

There were intellectuals.

But it also had a
skilled labor force.

- [Narrator] Nearby,
yet strangely forgotten,

were the Gusen subcamps.

[dissonant string music]

- This is the Gusen River.

We are inside the
concentration camp now.

- [Narrator] Prisoners
from these camps

provided slave labor for
construction projects

undertaken by the Reich.

- We are here, now,
standing in front

of the so-called
Schleppbahnbrucke Bridge.

A bridge that was designed

by the SS of St.
Georgen and Gusen,

and constructed by inmates
of concentration camp Gusen

in only one day and one night.

- Even with the forced labor

that they had available to them,

it's an engineering feat
however they did it,

if they did do it in such
a short period of time.

- [Rudolph] This
bridge was constructed

to link Gusen Concentration Camp

with the river system
of the Third Reich.

Over this bridge
all the material

of the concentration camp,
even transfers of inmates,

were sent also from
other concentration camp

into Gusen via this facility.

- [Narrator] Why
were the Germans

building up the Gusen
area so quickly?

And why the rounding
up of highly skilled

and technical labor?

- Ah, yes, you
could see it here.

- Here we are.

- [Narrator] Back
at the rifle range,

Andreas makes another discovery

that leads to even
more questions.

- It's much too
massive and too high

for a shooting range.

- [Narrator] Who
buried it and why?

And why did authorities
stop him from digging?

- They immediately stopped

all further investigations
on the spot.

- So, the authorities
say one thing,

but Andreas has a
complete different theory.

Who's correct?

[suspenseful instrumental music]

- [Narrator] World War II,
Bergkristall was a network

of tunnels covering
over 530,000 square feet

under the hills of
St. Georgen, Austria.

- One of the largest underground
facilities ever built.

- [Narrator] The tunnels
were dug in just over a year

by thousands of slave workers

from a nearby
concentration camp.

Seven decades later, documentary
filmmaker Andreas Sulzer

has made a surprising discovery.

- I think we are very close.

It's here on top here.

- [Narrator] Andreas
found a tank barrier

buried 16 feet underground
at an old SS Rifle Range.

- Why, why to build
any barrier here?

- [Narrator] He
made this discovery

while investigating another
strange clue he'd found

at the rifle range.

- We found a very detailed
supply intelligence report

of an informant

who gave an exact location

north of the known Bergkristall
for an underground entrance.

One kilometer north of
St. Georgen after the road

is an SS Rifle Range.

And just north of
it is a mountain

where a large excavation
has been made.

Excavation is about
200 square meters.

[intense instrumental music]

So, here is the
Bergkristall entrance.

So, here, is the rifle range.

And then he says, just north
of Edtsdorf and running

in a north-westerly direction
is a low range of hills.

For a distance of
about 3 kilometers

numerous excavations
have been made.

And that's all before
Bergkristall was built.

- [Narrator] After
excavating 16 feet deep,

they made a discovery.

- We found a concrete plate.

And then we found a stair.

[clock ticking]

- There's an interesting
mystery here.

- The stair always
leads to something.

- What's there?

What's Hitler got to hide?

- [Stephan] And then
we digged, and digged,

and digged down there.

- [Andreas] Yeah, and then
you go for the next stair

and for the next stair.

Crazy, absolutely.
- And for the next stair.

- So, also, the
structures you see here.

These really good
made structures.

- [Andreas] So, it's a
very strong building here.

- It seems like
every passing year

since the war has ended,

people are finding
new Nazi tunnels,

new Nazi trenches,
new Nazi bunkers.

I mean, just remarkable.

- And here was a kind
of a generator built in,

because here is a tank.

It's a tank, it's a full
container for a generator.

And here we ended up.

We were stopped by the
authorities, by the police.

Suddenly, one day
before Christmas

the police came and stopped
the whole excavation.

Within two weeks,

the whole property
of the SS Rifle Range

was immediately put
under cultural heritage.

No digging, no excavations,

no analysis.

And Bergkristall was set

under cultural
heritage months later.

- [Narrator] Why would there
there be secret tunnel entrance

buried in the back
of a rifle range?

Why have the authorities
gone to such effort

to stop Andreas from
investigating, even
at Bergkristall?

[intense instrumental music]

Construction work for the
tunnels began in early 1944,

and would be continuous

until the area's
liberation in May of 1945.

But why was it built?

- By 1944, it's clear
to anyone who is sane

that Germany is losing the war.

Surely, there can be no
hope for the Third Reich.

The Allies have got
complete aerial dominance,

which means that they can
attack almost at will.

And the Luftwaffe,
the German Air Force,

almost aren't able to put
up any kind of resistance.

- We do know that
some terrible things

were happening in these tunnels.

None of that is conclusive,

and it's not open
for discussion.

That's the Messerschmitt Me 262.

- The Messerschmitt 262 was

the world's first
jet fighter plane.

And it was a game
changer for the Germans,

because the Allied
planes at the time

were all propeller-driven.

These jet propulsion
planes could pass

all of these propeller
planes in the air.

- [Narrator] The Me 262 could
fly 93 miles per hour faster

than any Allied fighter plane,

up to 530 miles per hour.

And a jet could hold
its speed in turns

much better than a
propeller-driven plane.

- By now the Allied
pilots have become

so accustomed to
dominance in the air,

that the Me 262 when
it arrives in the skies

blows them apart,
quite literally.

They've never seen
anything like it.

The fighter flies past them

and tears into the bombers.

- Nobody could imagine
such a ferocious weapon.

They had a fighter version
known as the Swallow.

They had a fighter bomber
version knows as the Storm Bird.

The Nazis had claimed
just at the end of the war

that these two types of Me 262s,

that they shot down
550 Allied craft.

Imagine if they
had brought those

on line in 1940, '41, or '42.

- Having the world's first
jet fighter on your side

is a huge leap in technology.

They would be so
much more effective

than anything else in
the skies at that time.

But if this was gonna play
to Hitler's advantage,

he needed to get those
planes up in the sky

winning the air battle
as quickly as possible.

- [Narrator] The airplanes
were built entirely underground

on assembly lines
nearly a mile long.

- Why would you manufacture
a plane in such conditions

when you could have
manufactured it above ground?

- The only thing I can really
thing of is protection,

protection from
bombing, and the ability

to just continue to work
without interruption that way.

- Clearly, you're delaying
any kind of project

when you decide to
bury it underground.

You only do this for projects

of critical and
national importance.

And it's hard to imagine
a project more important

for the Nazi war
military machine

than the development of
the first ever jet fighter.

- In order to achieve

this underground
production facility.

I mean, they were
basically building

an aircraft factory underground.

They had to tunnel
out on a scale

that they'd never done before.

- [Narrator] The
Bergkristall plans called

for 19 main tunnels and nine
cross tunnels at right angles.

Each tunnel was 15.4 feet high,

and reinforced with concrete
on the walls and ceiling.

- The workers would dig
vertical shafts with shovels,

and then use air
hammers to blast

their way through
the ground, outwards.

The earth would be loaded
onto huge conveyor belts,

which would move the soil
away from the tunnels.

It was then loaded onto carts
and wagons to be taken away.

- As soon as they
built these tunnels

they needed to build
cribbing and shoring

to create structure to maintain
the shape of these tunnels.

That was likely done
by using timber,

and later installing
a concrete shower.

They would also put
a concrete floor on.

- And Hitler demanded

that this facility
would be up and running

within a year of
them breaking ground.

From an engineering perspective,

that's giving you
one big headache.

- [Narrator] It would
take 3,000 prisoners

working 8 to 12 hour
shifts almost a year

to carve out this space
beneath the earth.

- This facility had its own
septic sewage treatment.

It had its own heating,
ventilation, and
air conditioning.

- Any testing of these planes

would have generated
large amounts of exhaust

within these tunnels,

which would have rendered
the air quality very poor,

and made it extremely
difficult to breathe.

- The underground tunnels,
they're like a city in a city.

It's almost like an ant heap.

There's a huge
amount of activity.

And it's all working
together to produce planes.

- I can't imagine building
not just an airplane in that

but a brand-new type of
warplane that's jet-powered.

And then on top of all of that

bringing it up and
launching these things,

it boggles the mind.

- Do you build it in pieces?

Do you build the fuselage
separately from the wings?

And then do you put
that together outside?

The logistics of it just become
significantly more onerous.

[unsettling instrumental music]

- [Narrator] Despite
all the complexities,

German records have
the tunnels finished

and the jet fighter
assembly line

up and running by March, 1945.

[urgent piano music]

At the height of production,

there were a rumored
11,000 slaves

working underground
at Bergkristall.

- These were prisoners of
war, were foreign workers.

These are the people that
would have been responsible

for building these planes,

and many would have
died in the process.

- [Narrator] Only two
months after its start,

the jet production was stopped

in anticipation of the
Allies' push into Austria.

By then the plant had already
built nearly 1,000 planes.

But why is the existence of
other nearby tunnels in dispute?

- What's interesting is that

the jet plane production
was already decided.

So, we speak about two
different productions, maybe.

What's the question text for?

- [Narrator] What
secret new terror

were the Germans
building in the tunnels

beneath the Austrian
countryside?

[suspenseful instrumental music]

1944, the war has not been
going well for Germany.

And the Nazis are
desperate for an edge,

something that will turn the
tide of the war in their favor.

- By now swarms of Allied
bombers are hitting German,

military, industrial,
civilian targets.

Anything that makes
anything, moves anything,

they're gonna bomb it.

The Germans need to
come up with an answer.

- [Narrator] The
Nazis approve plans

for a 530,000
square foot complex

buried deep beneath St.
Georgen, 10 miles east of Linz.

Filmmaker Andreas Sulzer's
recent findings in the area

raised questions that
authorities dispute.

Could the tunnels extend
farther than Bergkristall?

- This is also very interesting,

because here is
also the stone wall.

And here is a plate
on that stone wall.

So, if this will be the end,

here will be a
concrete fundament.

But this is definitely a wall.

Same thickness like that,

so there is something
beyond this wall.

- What do you think the
stairs goes down, again?

- It's also possible
that it turns here

in the middle somewhere, again.

An angle to get down.

It looks like a--
- A small platform

then it goes right, then,
maybe, down to here.

- We're already deep down here.

So, it's up where is
the starting point.

It's eight meters.

- [Stephan] Yeah, I think so.

- That's unbelievable
and it's not the end.

- It's not the end, no.

- But we were forced to
leave the excavation site.

Everything is forbidden
here now, yeah?

- [Stephan] Yes.

[unsettling string music]

- Related to Bergkristall,
of course, is Mauthausen,

but much more related
to Bergkristall

are the Gusen
Concentration Camp.

- [Narrator] While
Mauthausen is one of the

most visited by tourists,
the nearby Gusen Camps

were completely
forgotten until recently.

- I started more
than 30 years ago

to research on that
lost history of Gusen,

because nobody didn't know
anything here in Austria.

- I'm born here in Linz.

I went to the school.

I studied here, but I
first heard in my life

with 45 years

that Gusen existed.

I never read about that before.

[somber instrumental music]

- So, Mauthausen was not only
a large concentration camp,

it was massive because it had
approximately 100 subcamps

or satellite camps stretching

across a vast territory.

Perhaps, the largest
of Mauthausen's
subcamps was Gusen II.

And Gusen II was particularly
bloody and gruesome.

In 1942, so many
prisoners were dying

that Gusen II builds
their first crematoria

to start burning all the bodies.

- When we talk about Gusen,

we talk about an unknown camp,

a still kind of secret camp.

Why is Gusen not
known to the public

or to a wider community?

- [Narrator] After the
war, most of the camp

was destroyed by the
occupying Soviets.

They didn't want to
commemorate a place

where so many of their people

had been imprisoned and killed.

- In 1947,

the Soviets even placed 54 bombs

inside the tunnels
of Bergkristall.

So, it almost collapsed
after this big explosion.

And, therefore,
Gusen was forgotten.

And the Republic of Austria
did nothing after the Soviets.

- Gusen, more or less,
was a death camp.

There are nearly no survivors.

Nobody could speak about
the situation here.

- [Narrator] Could
there be a connection

between the forgotten
camps of Gusen

and the mysteries
in the tunnels?

- But Gusen was not only a
concentration or a death camp,

it was also a high-tech

industrial park of the SS.

The longer the work got,

the importance of Gusen
increased, increased,
and increased.

- From mid-1944

the SS starts

to pick skilled workers
under the prisoners.

For example, miners for
underground building

and sent them over
here to Gusen.

And in the later
course of the war,

you see that they select
physicists and chemists.

They must work on
some special projects.

- [Narrator] Why
were some of the most

highly skilled prisoners
being brought in from camps

to work in the area?

[airplane engine roaring]

As the tide of the war turned,

Hitler relied more and
more on wonder weapons,

technological breakthroughs

that he believed would give
the Nazis a much needed edge.

- The Nazis made
impressive progress

on these terrifying
weapon systems.

The V-2 rockets, they
were working on a V-4.

These things were
just state of the art,

futuristic weapons of terror.

- [Patrick] If you look
at the Nebelwerfer,

which is the multiple
rocket launching device

strikes fear in the Russian
troops they fought against.

And it's leading technology.

- Surely, there's some wonder
weapons we don't know about.

A lot of their most impressive
weapon systems are coming

on line right at
the end of the war.

- Propaganda is promising
this to the German people.

These Wunderwaffe, they're
coming, they're wonder weapons.

So, the German engineers and
scientists need to deliver.

Is the wonder
weapons gonna be able

to get them out of this disaster

that they created
for themselves?

- [Narrator] Could the other
tunnels nearby have been built

for another one of
Hitler's secret weapons?

- It's almost as if
they believed they're
gonna win the war,

perhaps, with what they're
building in these tunnels.

- [Narrator] Seven decades
after the end of the war,

Andreas has discovered
something in the tunnels

that set alarm bells
ringing for his team.

- Was there something
more happening down there

than just the assembly,
the Messerschmitt 262?

- [Narrator] May 7th, 1945,

the Allies arrived
at Bergkristall,

a massive underground factory

where Germans had been building

the world's first jet engine
plane, the Messerschmitt 262,

only to discover its secrets
destroyed and buried.

- All of the sudden there's
a new type of flying vehicle

that blows by them at speeds

that they thought were
logistically impossible.

- [Narrator] Seven
decades later,

new discoveries
prompt some to wonder

if the tunnels run deeper
than anyone suspected?

- A lot of what the
investigation is
finding down there is

certainly opening up
unanswered questions.

- [Narrator] Documentary
filmmaker Andreas
Sulzer believes

there's more than
just Bergkristall.

His excavation at a nearby
rifle range has provided him

with some clues.

- Before we started
excavating there,

we made a geoelectric
on top of the hill

of the rifle range.

If you go further into the hill

where it rises up, you
see this structure inside.

And that's the resistance of
air and concrete here around,

so there's inside the hill.

- Two underground?
- Yeah.

It's huge structure
in that hill.

But the Allies, it
looks from the air

likes it's just a
simple shooting range.

But in my opinion

and based on the other
things we found here,

it's a very good
camouflage entrance

into underground facility here.

That would be really,
really interesting

to excavate all here.

I can't face it why
the authorities don't
want to dig here.

It's what's so
important to find out

what's inside here in the hill.

And there is something in there.

- [Narrator] Though
much lies in rubble,

Andreas has discovered
a curious clue deep

within the tunnels
of Bergkristall.

- When I was in the Bergkristall
Tunnels, first time,

I had a Geiger counter with me.

It's normal when I enter
underground facility.

You never know.

We saw 2.6, 2.8
microsieverts per hour,

which is 20 time
higher than the normal.

- Andreas is claiming
that the radiation levels

he measured when he went
down into these tunnels

is far higher than anything

that would normally,
naturally occur in geology.

- [Narrator] In January of 2015,

historians at Mauthausen-Gusen
convened a panel

to address the ration question.

- The Austrian authorities
are very clear.

They say that the
radiation is natural.

It comes from the rocks
and the surroundings.

- Radiation can come strictly
from natural surroundings.

However, the radiation levels

that Andreas would have found

are suspect, especially
if we do not know

what this official
source of radiation is.

- [Narrator] Whatever the
source, the radiation levels

are high enough that the tunnels

are closed to the
public 362 days a year.

- Well, these tunnels are open

for a very brief period of time.

They require scrubbing basically
to clean the environment

of radioactive materials.

That's a huge undertaking to
do and very expensive as well.

- [Narrator] So, where is
this radiation coming from?

Is it purely natural?

Andreas has other
darker theories.

- In the course of the war

when the SS got more power,

they moved in also
top secret projects

under the wings of SS
General Hans Kammler.

He was one of the most powerful,
high-ranking SS generals.

When the Allies
attacked Peenemunde,

the famous Peenemunde
rocket production,

Hitler ordered Kammler
to move all the rocket

and wonder weapon
production underground.

And Kammler was
responsible for that.

- [Narrator] Andreas
believes that Kammler

may have had an atomic
weapons facility

built in secret
tunnels beneath Gusen.

- He erected hundreds of
underground facilities,

partly in old mines,

but also with new
underground buildings.

One thing is quite clear,

Kammler shows up very early

in the area of St.
Georgen and Gusen.

And this has nothing to
do with Messerschmitt.

This has to do with his SS
secret weapon production.

So, there must be
something else.

[suspenseful instrumental music]

- [Narrator] Why
have the authorities

stopped Andreas
from investigating?

- The Americans had some hints

that there must be here
also underground facilities.

- It's really amazing.

- [Narrator] Could the
tunneling have been

much larger than
just Bergkristall?

[urgent instrumental music]

In the span of just over a year,

over 530,000 square feet
of tunnels had been dug

near the small town of
St. Georgen, Austria

by thousands of slave workers

from nearby concentration
camp Gusen II,

which until recently
was all but forgotten.

In these tunnels the
Germans would set out

to build fuselages for the
first jet engine aircraft

they hoped would turn
the tide of the war.

- While this miraculous
underground machine
is happening,

building these planes, you've
got these auxiliary tunnels

that are nearby that
we don't even know

the extent of them yet.

- [Narrator] Filmmaker
Andreas Sulzer believes

that the entrance
he found is part

of a secret tunnel system
codenamed Esh-shay.

- Esh-shay was a project
by organization Todt

also involving the
deaths and the SS

for underground production
to St. Georgen, Gusen.

You see here at the rifle range.

You see here a huge structure

on top of the hill.

And also here are shafts.

So, that's in here,
that's the area.

We excavated this entrance.

So, when we go a little north

at the workhouses for Esh-shay.

And here lived, based
on other documents,

German engineers,
workers for the Esh-shay.

So, this is already proof
that Esh-shay was realized.

And we also have
other documents.

But what is really,
really interesting

that the Americans
tried to bomb this area.

So, you see very close by--

- Intensive bombing.

- Intensive bombings.

You see here the bomb craters

which are partly
filled up, again.

But the Americans had some hints

that there must be here

close in that area also
underground facilities.

- These are things that
people are working on.

They're not meant
to be found out.

So, it shouldn't be
surprising for us

that we still have
things to find out

about what these men were
doing in these tunnels.

- Okay, let's have a look.

- [Narrator] Andreas and Stephen

have explored testing tunnels

they believe are part
of the Esh-shay system.

- These tunnels were setup
and built in autumn 1943

onwards to 1944

in order to test the
stability of tunnel systems.

So, they built different
tunnels in different depth

of the sandstone.

And they exploded on top
of the hill different bombs

in order to simulate if
the tunnels would break in.

When we, first time, went
in the test tunnel Esh-shay.

So, after some hundred
meter it goes deep down.

- It's really amazing.

- [Andreas] And it's broken
in from the explosion,

so it's not possible
to go further.

- They dropped the
bombs from outside

and the structure was broken.

- And, of course, it's
very dangerous going

in here, down deep,
because when you are close

to the breaking point,

you can feel while walking

that beneath your feet
is another tunnel.

So, the ground
starts to vibrate.

It's really dangerous
to go in there.

It's a very dark,

scary place.

It was made by hand with picks

by the prisoners, so
you see the scratches.

It's quite possible
that from here

directly underground
is a connecting tunnel

to the underground
facilities in St. Georgen.

- I think you could
go down and down here.

It's really amazing.

It's so big.

- They made, I think,
three to four tests,

but the really
interesting thing is

there's a testimony from
a survivor, prisoner,

who attended the last test.

And the last test was a bomb
underground in the tunnel.

Prisoners and sheep were brought

into the tunnels underground
close by the explosion space.

- I heard from
local eyewitnesses

that when the
detonations were done

that they have seen mushroom
clouds went into the sky

already in March or April, 1944.

And even three, four kilometers
away of the detonation point

the roofs of the
farmhouses were damaged,

all the windows were damaged.

This was not an--
- This particular air

is from a shockwave.

- [Rudolf] It was not
an ordinary explosive.

- And after that explosion,
a special commission came

and the whole area was shielded.

Nobody was allowed to enter.

And we found that
on the same day

when the commission came,

Wernher von Braun
is flying to Lintz

in his one day on
a secret mission.

- [Narrator] Wernher
von Braun was Germany's

top rocket scientist later
captured by the Americans

to work on the Space Race.

Why would he be
conducting secret

and urgent site
visits to this region?

What else was being created
in the tunnels here?

- This is a very, very,
very threatening truth.

- [Narrator] Is there
an atomic facility

buried here at St. Georgen?

And if so, how close
did the Nazis come

to making such a weapon?

- Could the whole war have
been completely different?

[unsettling instrumental music]

- [Narrator] In the
aftermath of World War II,

the Allies liberated one of
the largest concentration camps

in all of Europe and destroyed
tunnels at Bergkristall,

a massive underground
aircraft factory.

Seven decades later,
evidence of radiation

has some investigating

whether there was more
going on in these tunnels

than officially reported.

- Officially, there's
only Bergkristall.

But we see in the documents
and evidence we have

that there is a complex
of underground system.

They dug about eight underground
facilities in the area.

[urgent instrumental music]

- [Narrator] Andreas
found a report

from the American
General George McDonald,

a military intelligence
chief, after the war.

- He visited personally
underground facilities

which were in size from
five to 26 kilometers.

So, we involved military
experts who proofed

all the aerial reconnaissance
and the reports.

Is it plausible?

So, you can see the
excavation spots

where the Nazi moved the spoil

from the underground excavation.

And our experts did
calculations on that

based on the size of the tunnel.

We are talking about
40 to 50 kilometers

in total in that area.

And officially known is
six or seven kilometers.

- [Narrator] But
Andreas found another

even more fascinating
note in McDonald's report.

- That's an interesting
point, certain.

It was recommended that
this paper be forwarded

to headquarters Army
Air Forces with the idea

of selecting targets of
above mentioned types,

this refers to the
underground facilities

mentioned or inspected,

for secret experiment of
rocket-propelled atomic bomb.

- Building an atomic
bomb, a nuclear device,

is extraordinarily complicated,

especially for
the '30s and '40s.

Remember, the Nazis are
on the cutting-edge,

and they're just beginning to
develop jet-powered planes.

They're just beginning
to develop rockets.

So, the idea of an atomic bomb.

This was futuristic.

- We know that the Nazis were
looking at atomic energy.

They understood the principle.

The scientists go to Hitler,

and they present
to him a roadmap

for how it could be achieved.

But there is worries
just about anyone else

about what Hitler
can do with this.

And so, they actively try and
dampen down his enthusiasm.

Hitler goes along with them,

and he doesn't make creating
atomic weaponry a priority

for the Nazi Reich.

But that doesn't mean

that the Nazis stopped
any investigation,

any scientific work,
into nuclear development.

On the contrary, in 1942,

they created what was known
as the Second Uranverein.

This project dedicated
to atomic bomb creation.

[tense instrumental music]

- [Narrator] But what
does it take to build

such an atomic weapon?

- You need to build a
particle accelerator

to fire neutrons at atoms

to split the atom,
which releases energy,

which causes a chain reaction

where other neutrons
split more atoms,

and that atomic explosion, that
explosion of energy happens.

[dissonant instrumental music]

- Before the rifle
range was excavated,

we had another spot where
they said, "There is nothing."

- [Narrator]
Andreas's team found

a 98-foot, sealed,
concrete octagon.

- In the aerial photographs
we see that octagon.

During World War II it's open.

But the SS sealed it some weeks
before the Americans arrived

and hid it with soil.

- [Narrator] During
the excavation Andreas

found an artifact that
might've given a clue

to the atomic question.

- It was a ceramic roll.

And it's part of a
particle accelerator.

We have original
photographs of this type,

which is from 1943,
the same piece.

And we sent those pictures
to physics institutes.

And they also kept
the confirmation

that this is part of a
particle accelerator.

- [Narrator] But Austrian
authorities disagree.

- They say it's a
part of a motor.

It's a wheel for a motor,

but it's definitely not
because it's ceramic

and it's very fragile.

And even the metal rings
are very, very thin.

- [Narrator] One week later,

the authorities
stop the excavation.

- So, the octagon

was immediately covered
again with soil.

So, it's, again,
away from the site.

- [Narrator] Did the Germans

have the resources
to build this?

- To have access to
that type of technology,

and the space that something
like that would've taken,

I'm just not sure if it
would've been possible

to do something like
that underground.

- This is not
off-the-shelf science.

This is specific,
it's expensive.

It's energy intense.

- [Narrator] The energy
from an atomic bomb

is released as both
heat and radiation.

Could this be the
source of radiation

lingering at Bergkristall?

- Officials claim that
any radiation detected

in this area is coming
from the ground naturally.

And that does occur in geology.

There's nothing
strange about that.

Another theory is
that this radiation

is coming from man-made
atomic programs.

Which is true, we
may never know.

[resolute instrumental music]

- It's hard to
believe that Hitler

wouldn't wanna pursue
the power in the atom.

He's power hungry.

Why wouldn't you
pursue that avenue?

- If there was just a
hint of a suggestion

that these tunnels were part

of a secret Nazi atomic
bomb creation project,

then the Allies would've
stopped at nothing

to get inside the tunnels.

- So, is it possible

there was some sort of
atomic research going on

at Gusen II or Bergkristall,

and the Allies grabbed
it and took it back?

Yes, it's possible.

We don't have any
evidence for it.

- One thing is for certain.

Had the Nazis got their hands
on nuclear capabilities,

[sighing]

the thought of that is
absolutely terrifying.

- I think if Hitler
had an atomic bomb,

he wouldn't have
hesitated to use it

to end the war to his advantage.

And I also think he
wouldn't have hesitated

to use it even if he knew
he was going to lose.

He's going to go out swinging.

To hell with anyone.

- It's shocking for me
not to be interested

to uncover the truth.

We owe it to the victims
and to the families.

And I think also
it's very important

for people who live here
or want to build a house

to know what's under your feet.

- Some people are obsessed
with finding the truth,

and they do that for
personal reasons.

Sometimes, they have
a greater mission

that they're working towards.

But if we can
understand what happened

in this particular
period of time,

which more than
any other conflict

has created the world
we live in today,

then I think that's gonna
be a good thing for us.

- [Narrator] As experts
continue to struggle

to find answers hidden in
the hills of St. Georgen,

we can only imagine
how far the Nazis got

in their atomic research,

and how many of their secrets
are still buried here.

[urgent instrumental music]