Original subtitles

The remains of a sinister walled complex,

lost to the freezing waters.

Why was this area flooded?

What did it use to be?

A forgotten passageway that leads into the depths of a mountain.

This gaping hole in the rock face

that looks like some kind of entrance into the underworld.

Strange military structures hidden in a snow covered forest.

There's something not quite right about this structure.

At first sight you think you know what it is,

then when you get closer, it doesn't quite add up.

And a huge industrial relic near the coast, in mainland Europe.

This elevated rail line just terminates

in this massive monolithic contraption.

(Upbeat music playing)

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 song plays)

In Estonia,

the eastern European country formerly occupied by the Soviet union,

is a complex with a troubled past.

A sprawling guarded compound,

partly immersed in a nearby freezing lake.

Andrew: This is such a curious site.

There's this lovely lake, only one problem,

there's been concrete structures in the middle of the lake.

What you see is this weird landscape,

nature's essentially taken over.

The way they sit there,

there's almost something apocalyptic about them.

In the depths of the lake is a bizarre sight...

Forgotten machinery, lengths of barbed wire,

and walls topped with floodlights.

The building's scrawled in graffiti,

juts imposingly out of the lake.

And a hill that looks strangely out of place,

in what is otherwise very flat terrain.

Sharp veins carved out of the steep slope

lead up to a tree covered Ridge, high above.

Could they give a clue

as to why these structures have been left to just crumble away?

It was not a place anybody wanted to be.

The clues are linked to the decades that followed

the 1940 occupation of Estonia and other baltic states

by communist Russia.

Some 500,000 Soviet troops took part in the invasion,

which saw the presidents of Estonia and Latvia arrested and imprisoned.

Rigged elections were organised,

that resulted in new Soviet puppet governments being installed,

that immediately requested admission into the Soviet union.

They were graciously accepted.

Soon there were mass deportations of enemies of the people.

It was just the beginning of the sovietization of the baltic states.

The Soviets began to implement huge infrastructure projects

across their new empire,

which created a desperate need for construction materials.

And this partly submerged site was all part of the Soviet plan.

This is rummu prison,

but how was it linked to the Soviet search for construction materials?

When the Soviet union begins to occupy the baltic regions

and Estonia in particular, it gets really ugly very quickly.

(Dramatic music plays)

Anyone who voices opposition to the Soviets,

more often than not, they're put into a prison.

This was one of the most oppressive prisons in all of Europe.

It was not a place anybody wanted to be.

The prisoners lived and worked, in inhumane conditions

and were treated harshly.

(Soft music playing)

Andrew: It was a place you were put as punishment,

and the punishment was very severe.

But in the Soviet union,

prisons weren't just used to lock up inmates,

they were brutal places for hard labour.

So, what did they need an army of workers for here at rummu prison?

This part of Estonia is really famous for its limestone quarries

that produce this material that was really easy to process.

Dougal: Pure ones, have this kind of marble-like quality.

They're very light in colour, they don't have many impurities

and it means when you want to use them for things like cement

and when you want to use them in the paper industry and so on,

they are the ideal type of limestone.

It may not look like it now,

but in 1938, a quarry was built here at rummu prison.

It's aim was simple,

to excavate vast amounts of limestone.

And the size of this strange hill is a clear sign

of the extent of the operation.

In terms of mining,

a slag heap is essentially, the rocks that you don't want,

and so as you process the rocks and mine them,

if you've got an area, which you're collecting

and say 50% of the rocks are good and the stuff that you want,

and the rest is really rubbish,

if the mine has a long life to it,

these slag piles could be almost like small mountains.

But without giving the inmates heavy machinery,

how was the limestone removed?

They'd actually just blast the areas with dynamite

and collect the limestone accordingly.

The reason why the Soviets built a prison next to this quarry

is that really you just need sort of brute force

to get the rocks into smaller pieces so you can transport them away.

So, if you can have a large labour force

they don't have to be particularly that skilled,

that can attack the rock mass in terms of breaking it down

into smaller pieces so you can take it away,

then that's ideal for you.

To prevent escape the site was surrounded

by heavily guarded security fences, which were lined with barbed wire.

But as demand increased, a new unexpected complication arose.

Could the over-use of manual labour

have contributed to the flooding of the site.

As you go further and as you potentially go deeper,

then you might encounter some problems.

For example, you might start to get into ground water

and this is clearly an issue that happened at rummu.

As they dug deeper, water began to pour in,

creating dangerous conditions and bringing work to a grinding halt.

To clear it out, pumps were installed in a central building.

Working the mines here would have been a very physical challenge

and clearly if you're in an environment

where it can go below zero in winter.

They're constantly pumping ground water up,

you're not being fed very much.

This would have been very harsh conditions for anyone to work.

The sheer amount of ground water that's flooded back into the mine

shows you just how far they were going to extract the resource.

The site was originally constructed to house just 400 inmates.

But when they struggled to fulfil their quotas,

the police came up with the simple solution,

to increase the number of workers.

The way the Soviet's coped with the acute labour shortage

was by forced labour in prison.

Forced labour of things that nobody wanted to do,

even if you paid them, 'cause they're difficult,

they're back-breaking and they're long, long hours,

no one's going to sign up for that.

So what do you do? You make them do it.

You put them in prison and say, "this is your job."

Whenever they needed more workers,

there'd be more arrests for hooliganism.

Many of the prisoners were sentenced for social crimes,

effectively, public order offences.

According to a CIA report,

the local area was home to three forced labour camps.

Together they housed a combined workforce of 5,200 prisoners.

Many prisoners died because of cruel treatment,

poor food, and appalling working conditions.

There were rooms dedicated to psychic and physical torture.

And if you resisted too much, they took you into another room,

where they asked you to kneel down and put your head against the wall

and they shot you in the back of the head.

(Gunshot)

But how did this place end up in a watery grave?

When the cold war ended and Russia vacated Estonia,

you know, there was no political appetite of any kind to maintain,

you know, what they had created and why would there be?

It was a place of oppression, it was a place of death

and so they just let it go.

As communism retreated, conditions at the prison began to improve.

Forced labour was ended, the quarry site was closed,

and the pumps were switched off.

If you're excavating below the level of ground water

and you're pumping the ground water out

to suppress that ground water from flooding the mine,

obviously the minute you turn the taps off,

it's going to start flooding again.

The rising waters swallowed up machinery and buildings

before they could be saved.

But the surviving section of the prison

remained in use for another 20 years,

finally being abandoned for good, in 2012.

Today the prison is a stark reminder of a cruel and vanished empire

and of a discredited penal system.

5km south east of waynesboro, Virginia usa,

in the blue Ridge mountains there is an ominous site.

In the depths of the forest is a hidden archway,

cut straight into the middle of a hillside.

You're faced with this gaping hole in the rock face,

that looks like some kind of entrance into the underworld.

(Soft dramatic music playing)

Once you get inside, all you can make out

is this dark passageway disappearing off into the distance.

1.5km away, buried far inside the woods

is a second entrance to this underground lair.

There's something pretty spooky about it.

You wouldn't want to go wandering off on your own too far.

But deep inside a wall blocks the route.

Did the two sides ever connect

and what exactly was this underground site built for?

The answers are hidden in the history of the United States,

as it underwent a dramatic transformation around 200 years ago.

This was the age of industrialisation,

when the appearance of steam boats and railroads

and the invention of communication devices such as the telegraph,

made trade possible throughout the vast ways of the country.

The market economy and the factory system,

which were rare beforehand, began to flourish

along these new transportation routes.

The east coast towns were booming,

but the blue Ridge mountains part of the mighty appellations,

formed a natural barrier to the heart of the continent,

all but cutting off trade links to those central areas.

As a mountain range they're not particularly big

but they're made up of very, very hard rocks.

There's old metamorphic rocks, there's granites in there,

and so any topography like that becomes a big, big problem.

To travel across the mountains you had two choices,

either along a canal at a painful four miles an hour

or in a bone-rattling stage coach.

To speed up the crossing,

plans for a new tunnel system were quickly drawn up

and in 1850, work started on this unique design.

It's narrow and high, 16 feet by 21 feet.

That's quite an unusual shape to have for a tunnel.

We're used to having quite rounded gradual curves.

Could the unusual shape be the key to success?

Alan hale, is a local expert on the history of the structure.

Initially the impetus was to build canals

but ultimately it was seen that the best means of transportation

as it came towards the middle of the 19th century

were railroads.

It was planned as a 1.5km long underground track,

masterminded by French engineer, claudius crozet,

it would become known as the crozet tunnel.

This is a real feat of engineering.

They did it by hand, by sweat, blood and tears,

with only essentially gun powder to help them on the way.

But there are no rail tracks here, today

and walls inside block off the tunnel.

So, what happened?

When you want to build a tunnel from one side of a mountain to another,

you look at the rock types.

Ideally you want a soft enough rock that you can carve into,

but it has to be hard enough to maintain a tunnel.

In the blue Ridge mountains there's a particular problem

because the rocks are quite hard.

You've got granites on one side

and you've got greenstones on another,

this kind of metamorphic volcanic rock, that's very, very hard.

How would they cut through almost 1.5km of solid rock?

Construction techniques for tunnels at the time

were a far cry from what we've got available today.

So much so,

that progress went at about one foot a day into the mountainside.

This tunnel was drilled by hand,

you can see remnants of these drill holes.

Here's one up on the wall there.

One man swinging a sledge hammer

and another holding a bit, which turned and turned and turned.

It would be about three feet at the most

and then shot with black powder.

Black powder is dangerous because at best it's unpredictable.

Many deaths, many casualties would have occurred because of that.

But this was not the only danger that faced them.

As you tunnel through a rock mass, the nature of that rock mass changes

and where you get faults or cracks within the rocks,

or you might get two different rock types against each other,

you can actually have water coming into those gaps.

The worry is that these areas where the water's coming through,

are actually weak.

So, what they had to do was to shore that up,

so they put in a thick wall of bricks

to essentially line that portion of the tunnel,

to ensure that it remained safe and stable.

The dangers of rock fall are Paramount.

This is indeed what caused many of the injuries and fatalities

during the excavation of the tunnel.

In total, 14 men died whilst working here

and many more were injured.

So as we are going into the tunnel here,

you'll see that all of this is real solid rock

and basically nothing has changed here from the 1850s,

when this was bored through the mountain.

As one of the six competing lines,

racing to cut through to the central states,

this Virginia route had to be completed quickly.

To double the speed, they went at it from both sides at once,

but did the unique slender design of the tunnel offer another solution?

Roma: The idea was,

in these very difficult conditions with the hard material,

to try and maximise the amount of area of material

that the men were working on at any one point.

People really doubted crozet

and whether his design was actually going to work,

whether he could really pull this off.

The tall shape meant that two separate crews

were able to work on the tunnel at the same time.

First the header crew made a start on the roof section.

Next the footer crew followed on,

digging through the lower level to create the floor of the tunnel.

It would effectively halve the construction time.

But as they were digging from both sides at once,

would the two tunnels line up and meet in the middle?

So, nearly seven years had gone by.

The workers had been working in very back-breaking conditions,

there were unstable explosives.

They had one of the coldest winters on record.

They were hit by cholera.

But one day, they actually got to the point

where they created about a two-inch hole

and you could see through from one side of the tunnel to the other.

They were only a few inches out.

They were almost dead-on-message in terms of where they were predicting

the one tunnel meeting the other.

Amazing engineering feat for that time.

When it opened,

it was the longest mountain railroad tunnel in the world,

stretching 1,300m.

Slashing the time it took to send goods across the mountains,

the valuable market in the west was now open for business.

Despite its great success,

as freight trains and carriages grew larger,

crozet's ingenious design became out-dated and too small.

So, if the tunnel was completed,

then why do the two sides not connect today?

In the 1950s, a gas company

was planning to store gas in the centre of the tunnel

and what you see here is a reinforced concrete bulk-head,

which seals off the interior 2,000 feet of the tunnel.

Ultimately,

that project failed but the walls blocking this tunnel remain.

Today the crumbling tunnel entrances are reminders of the sacrifices made

and the bold ambition of the engineers,

who hoped to build a better future for the United States.

At the end of the day the structure was used,

and it did help the country and the economy of the local area.

I have a lot of admiration for the tenacity of the engineers

to make sure that this project, got built.

45km from Finland's capital, Helsinki

stands a pair of abandoned towers.

Located in a snow-covered forest,

these identical structures are hidden amongst the trees..

At first sight you would assume

this is just a standard European medieval church.

But there's something not quite right.

Only when you get close

can you see that this is not made of stone;

it is made of poured concrete. It's got to be 20th century.

Locked up and sealed off for decades,

were the locals here trying to forget past events?

(Dramatic music plays)

The towers' construction hint at a sinister purpose,

like they're designed to withstand an apocalyptic event.

The tower itself is very massively built,

I mean, it's really solid.

And when you get to the top of the tower,

instead of coming to a point, you've got a very obvious platform.

Seen from the top is the small town of rajamaki,

dominated by a large industrial looking building.

The tower looks like a castle tower

but... and it's for the same purpose.

It gives you a very high elevated view of the ground around you,

but critically here,

it gives you a very high elevated view of the air around you.

So, why were these towers built?

And why are they here, deep in the finish countryside?

To unpick the mystery,

clues can be found in a forgotten chapter of the second world war.

In November, 1939, three months into world war ii,

the Soviet union invaded Finland.

It became known as the winter war.

It began after the Soviets demanded

that Finland give up large areas of border territory

in exchange for land elsewhere.

This was officially for wider security reasons,

but mainly for the defence of the vital port of Leningrad,

which was 32km from the finish border.

Finland refused and the Soviets invaded.

In temperatures as low as minus 43 degrees celsius,

the fins, at first, managed to repel the attacks,

but the Soviets re-organised

and the fins became hopelessly outnumbered and outgunned.

The Soviets had around 3,000 tanks. The fins just 32.

They were in desperate need of effective defence.

David: As far as Stalin's concerned,

there is no way a country the size of Finland

with a tiny population

is going to say no to the might of the Soviet union.

Unfortunately, the fins had other ideas.

One way of improvising an anti-tank defence

was the creation of the molotov cocktail.

Simply a bottle filled with kerosene, tar, gasoline mixture

and it could be ignited by a sulphuric acid fuse.

Simpler versions of molotov cocktails,

made from a bottle of petrol with a flaming rag in the top,

had been used in conflicts across the world

ever since the Spanish civil war.

But it was the fins,

who first realised its full potential as a weapon in guerrilla warfare.

Desperate times required desperate measures

and the molotov cocktail ranks there pretty high as a desperate weapon.

It's a very, very dangerous way to attack the enemy.

David: However likely armoured a tank might be,

if all you've got is a uniform,

a rifle and a bottled filled with petrol,

it takes a lot of guts to try and sneak up on it,

to try and get close enough

to plant your petrol bomb on its vulnerable area,

which is the rear deck above the engine.

To manufacture enough molotov cocktails

the finish army go to the state alcohol plant at rajamaki.

They take bottles of alcohol

and there they are manufactured into molotov cocktails.

It's fire bombs on an industrial scale.

Incredibly,

the Soviets suffered five times as many casualties as the fins.

But with their superior numbers

they stepped up their attack and the molotov cocktail factory

soon became a key target.

There's a problem though,

because this is a state alcohol plant,

it's got the name of the alcohol plant on the cap.

When the Soviets find these caps,

you might just as well have held up a big flag saying,

"the enemy is here."

It's now very easy to find where these are being made,

and thus it's very easy for the Soviet bombers

to arrive and target the factory.

Plans were quickly drawn up to bolster the town's defences.

If you're looking at Finland,

one of the main problems the landscape offers

to any anti-aircraft gunner,

is that there are an awful lot of trees in the way.

The only way to extend your horizon,

to get yourself a clear field of fire for incoming bombers,

is to lift your anti-aircraft gun off the ground.

And that's why the only solution was to build a tower.

Standing just 500m away from the bottling plant

are the rajamaki towers.

Each was built to hold an anti-aircraft or flat gun,

capable of unleashing deadly fire upon approaching enemy aircraft.

A flat gun is simply an artillery piece,

which is made with a high elevation on the barrel

to bring aircraft down.

It will shoot a shell high into the air,

that shell will burst near the aircraft, hopefully,

and the bursting fragments will bring an aircraft down.

The towers could provide the ideal defence

but with the Soviet attack imminent, would they be ready in time?

The fins were rightly fearful.

The Russians really didn't have the capability

to drop bombs with precision,

so Finnish towns would just be carpet bombed.

The war was moving from the ground to the air

and the fins would have to scramble a strong defence once again.

In rajamaki two bofors, 40mm anti-aircraft guns,

were brought in to defend the bottling plant from the ground.

40mm bofors gun was probably the best,

one of the best anti-aircraft weapons ever invented.

Very advanced gun for its time,

but not fully automatic by any means.

It had to be loaded by the crew, themselves.

In the Finnish winter,

when everything is blanketed by snow, it must have been freezing.

Any wind blasting across the landscape

is going to hit that crew full on.

The gun layers themselves,

who were actually looking for targets, sighting targets,

the crew, who are loading ammunition to it,

simply can't be standing there completely wrapped up in furs.

They've got to be mobile.

It must have been quite grim for that crew,

waiting hour after hour

to be able to take on a bomber and keep it away

from that vital bottling plant.

Seppo pietarinen works for the local municipality

and knows the extraordinary history of the towers.

We are now on top of one of the towers

and here is the shaft where the anti-aircraft,

the gun has been lift up and placed here on top of this shaft.

The gun can spin around 360 degrees,

because the bombers can approach from any direction.

But just three months after it had begun, the winter war was over.

The area of rajamaki

had been the victim of nine separate Soviet bombing raids.

But the fins had held firm and the factory had survived.

The Soviet air force throughout the winter war,

the three months of the winter war,

lost hundreds of its aircraft.

Normal estimates were about 300-400 being shot down by the fins,

either by aircraft or ground defences.

The following year,

with the guns now mounted on the completed towers,

the war was suddenly back on.

The two towers would have been linked by telephone lines

and they would have been linked to commander control centre.

All through Finland you would have people with binoculars,

with range finders, on top of buildings

because Finland didn't have a radar system.

They relied on this fairly good, observer system

that would spot Russian aircraft,

give their altitude, give the position.

The flat guns would be alerted to Russian aircraft,

what route, what distance, what speed.

Put yourself in the position

of someone on top of one of those flat towers.

You're above the tree line

so, there's very little camouflage and cover for you.

You're in a position where the Soviet bombers

can see where you are shooting at them from.

They're going to target you. You are a sitting target.

It's going to take guts to be up there.

Although Finnish defences were very limited

and for example, here in rajamaki,

a gun or two on towers is not going to ward off dozens of bombers

if they really want to get through.

The deterrent factor was such that really any kind of resistance

would have had a major effect on an attacking force.

Even one gun could make all the difference

between protecting a site

and it being pulverised by incoming bombers.

With the towers and guns in place,

the Soviets never targeted rajamaki again.

The only bombers to fly over

kept themselves high above and out of range.

The towers had done their job.

When the second world war ended,

having sided with the Nazis, Finland was again on the losing side.

The bottling plant had reverted back

to producing alcohol rather than molotov cocktails

and the towers were locked up for good.

When you look at the towers today

they're a symbol of Finnish resistance against the Soviet union.

Everybody played their part and the towers really stand as testimony

to the efforts made by the Finnish people,

people who worked in factories,

people who fought the Soviets at the front.

They really are a testimony to the resilience of the people of Finland.

On the south coast of Spain is the city of almeria

and near to its heart, lies a huge industrial relic.

This rusting rail line stretches for nearly 600m.

It's a long snake-like structure

that extends out into the water from the city.

Jim: This elevated rail line kind of winds through the port town

and then just terminates in this massive monolithic contraption

that just kind of juts out into the bay.

Here, a giant steel pier supports the rail line

as it splits into four separate tracks.

Jim: Almost like the Eiffel Tower lying on its side.

So, clearly it's old, but what's its purpose?

Where does it go?

Its story is closely tied to the mass industrialisation of Europe

in the 19th and 20th centuries.

The economies of the continent were being transformed

from those that depended on agriculture

to new ones that were based on the manufacture of goods

of all descriptions.

Mechanised mass production was the key.

The factory assembly line replaced the individual worker

and the craftsmen and lives would change forever.

All of this new machinery needed material

and it was steel that became king, in the new industrial age.

Its key ingredient was iron ore,

and that, was one of the most sought after resources in the world

at the beginning of the 20th century.

But dark clouds were gathering.

Tensions between nations were rising

and the first world war was little more than a decade away.

But the old mines of southern Spain

just didn't have the infrastructure to meet the new demand.

The mines are located somewhere in land,

in a slightly mountainous terrain.

There's several hundred feet of topographic variation.

And that poses a problem because it's somewhat inland,

it might be easy to locate the iron ore

to essentially mine it out of the ground,

but you have to move it from there to somewhere where you can ship it,

so you have to get it to the coast.

The first part was simple,

to build a railway line between the mines in southern Spain and almeria,

the nearest port city.

But the real problem still lay ahead.

Jim: It's hard for most people to imagine today,

how low-tech ports used to be in their operations.

Everything that went on a ship had to be handled by hand.

Dan: Transportation of the iron ore

from the end of the rail to the ships

was an extremely laborious process.

Because by hand the iron ore was unloaded,

stored until a ship would come and then when the ship would come,

by hand, the iron ore was then loaded onto the ship.

Jim: Loading a ship full of iron ore might take a week.

It was an incredibly inefficient process.

What's so brilliant about this project is,

they completely re-imagined how you could load a ship.

With the new political instability across Europe,

the old port just couldn't keep up

with the increased demands of a rapidly changing world.

So, would this new hulking mass of steel speed up the process?

Construction began in 1901.

It would become known as El cable ingles, the English pier.

It was solving a very fundamental problem,

which was the amount of time and labour it took

to transport material.

They used engineering

to try and create a much more efficient and better way to do that.

Well the original design of the El cable ingles

was to be made out of wood, but in that particular region

there were storms and other environmental conditions.

It was decided that metal would be more appropriate and more suitable.

Dougal: Southern Spain seems somewhat idyllic to most of us,

but in the Autumn and winter months

it can actually have some quite violent storms.

So, clearly areas where you go from calm to storm, to calm to storm,

those kind of surges mean that

a structure for example, made out of wood,

might not be good enough to sustain for a long period of time.

The obvious choice of material was steel.

The invention of the modern steel making process

was kind of like the invention of silicon chip.

It was one technological change,

that then enabled all these other changes.

They used the capabilities of this beautiful material

to help them mine more iron and make more steel.

But with the future of the Spanish mining industry

relying on the success of this project,

why was it called the English pier?

England had the advanced steel mills that needed this ore.

They also had all the money, they had all the capital,

so they could afford to make these massive investments

in countries like Spain

and then a massive investment in the infrastructure

to get that ore to the port and onto the ships.

Designed by leading British engineers,

the idea was to leave all the heavy lifting

to the rail cars and the jetty alone.

Supposedly, the days of shovelling ore by hand were over.

But was there a new danger?

Instead of having to load the ships by hand,

they would roll the rail car

right out to the end of this high, elevated pier.

And they would dump the contents directly into a big chute

that led straight into the hull of the ship.

Along the length of each side of the jetty are 20 hoppers.

Using gravity alone to move the ore,

it would fall straight in to those great containers.

Then by selecting which chutes to use,

it was poured directly into the ships hold.

Would the modern system save the local industry?

I think it's such a neat solution to have the system

where the shoots take this material from a train to a ship.

Jim: In many ways it reflected the modern more mechanised way

that major ports work, today.

If you go to a container port like the port of Los Angeles,

you'll see these giant containers getting loaded on and off boats.

No one needs to touch the cargo, at all.

Dougal: It was a problem that needed to be solved

and the solution to that was a great increase in efficiency.

It was a process that used to take ten days,

now it only took ten hours.

It was a quarter of the original cost,

which was actually great savings.

This technology helped Spanish exports of iron ore

grow from just 500,000 metric tons in 1875,

to ten million tons by the Eve of the first world war, in 1913.

With all that growth,

why does the English pier lie abandoned

on the edge of the city today?

It has its period when it's perfectly optimised,

for the needs of the ships and then technologies move on,

markets move on,

other mines will open in other parts of the world.

In September 1970, it ran for the last time.

Originally saved from demolition by its historical value,

as costs increased,

major plans to convert the English pier failed to materialise.

So, for now, the old structure

continues to stand abandoned on the shore.

Roma: It's really impressive to me that the cable ingles lasted

and was used actively for about 70 years.

If you consider the rate of change

of technology and innovation at the time,

it really shows that they were ahead of their time

in the innovations that they used

and also it really solved a problem that needed to be solved.

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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