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This episode of Real Engineering is brought to you by Skillshare, home to over 20,000
classes that could teach you a new life skill.
As WW2 drew to a close and the race to Berlin reached it’s finale, two Soviet armies converged
on the Third Reich capital.
Marshal Georgy Zhukov from the North, and Marshal Ivan Konev from the South.
Motivated to beat the Americans and British to claim Nazi technology and plunder for themselves.
The Battle for Berlin raged for 17 days as the soviet forces surrounded the city, but
the Nazi’s surrender may have come sooner, if not for one of the largest defensive structures
ever built.
As the 150th and 171st Soviet Rifle Divisions began advancing across the Spree river, they
met the Zoo tower, located within the Berlin Zoo.
A behemoth structure built as a centre for anti-aircraft operations.
Equipped with four 12.8 cm Flak 40 anti-aircraft guns, together capable of firing 96 rounds
per minute, and with a group of 20 mm and 37 mm anti-aircraft guns on the lower platforms,
the Zoo Tower was a veritable death castle.
A death castle, with no glaring design flaw to lead to its destruction.
Any aircraft that dared enter it’s 10 km range was likely to meet its end, but on this
day the Zoo tower turned its attention to the ground and the approaching soviet armies
and began unleashing powerful and accurate fire.
Reducing their tanks to smouldering scraps of metal in short time, and halting their
progress.
The Soviet’s ordered the tower to be shelled at range from their most powerful 203 mm Howitzer,
a purpose built bunker buster, but the 100 kg rounds had little effect.
With 2.5 metre thick steel reinforced concrete walls, the tower was practically immune to
shell damage.
Even if a hole could be punched through with repeated shots.
The tower would remain standing, with no single load bearing structure it would take an immense
explosion to take down these towers.
The soviets instead decided it best to circle around the tower outside its effective range,
and later negotiate a surrender.
The Zoo Tower, was just the first of many anti-aircraft towers built throughout major
Nazi cities.
Berlin had 3 pairs of towers forming a defensive triangle around the city’s centre and central
government.
The first pair in Berlin Zoo, the next at Friedrichshain and the third in Humboldthain.
2 more pairs were constructed to protect the vital port of Hamburg, and finally 3 more
pairs were constructed in Vienna, Austria to form another defensive triangle around
the city’s center.
Amazingly, many of these towers remain intact, despite numerous efforts to destroy them.
Stark reminders for the inhabitants of these cities of an evil war waged by their ancestors.
The towers were ordered to be built by Hitler after the devastating and merciless bombing
raids of civilian targets in Berlin in 1940 by the British RAF.
Furious, Hitler demanded top priority for the project, ordering railway and shipping
traffic to be diverted to satisfy the 1600 tons of material needed for every day of construction.
With the help of forced labour the Zoo tower was completed in just 6 months and used a
total of 78 thousand tons of gravel, 35 thousand tons of cement, and 92 hundred tons of steel,
along with the immense amount of wood required for the moulds that formed the shape of the
towers.
To this day you can still see the outlines of the planks that formed this moulds.
Each tower complex consisted of a tower pair.
An attack tower, named the G-Tower and a communications tower called the L tower.
All communications towers took this rectangular shape, and came equipped with radio equipment,
spotlights, their own anti-aircraft guns and were tasked with coordinating the attack.
The attack towers came in a variety of shapes, with the earlier generation fortresses taking
this square form 42 metres high and 57 metres wide with turrets on each corner.
Later in the war, as supplies became more scarce, the designs took the form of these
16-sided circular structures, 50.6 metres high and 43 metres in diameter like this one
in Augarten Park in Vienna.
The attack towers were capable of firing 8000 rounds per minute, they formed a formidable
air defence within their effective range, but in all reality these towers had an extremely
unimpressive track record with downing planes, instead they acted primarily as a deterrent,
any bomber that dared stray into their sights would more than likely be shot down, but instead
they mostly just kept well away from these stationary positions.
Each complex had an effective range of about 10 kilometres, so the complexes formed an
important defence for the strategic positions they covered, but left much of their cities
unprotected.
But these towers were more than just flak towers, they served as valuable shelters for
the civilian populations.
Each tower had its own freshwater well and vast stores of food.
The towers had their own power generators, with underground supply lines for fuel, and
ofcourse massive stores of ammunition .The towers even contained hospitals, with one
tower containing a maternity ward where many Berliners were born during air raids.
Up to 15,000 civilians take refuge from the relentless bombing.
In the final days of the war up to 3 times that number are reported to have crammed themselves
into these concrete shells.
Leading to horrifying conditions with people dying in the cramped corridors with nowhere
to bury them, toilets overflowing, and the hospitals overflowing with injured and dead
patients
There are few visible signs of the devastation these cities endured during the Second World
War, thanks to the funding from the Marshall Plan, cities were rebuilt brick-by-brick,
removing the scars of the past.
But these buildings remain, a testament to the strength of their construction.
All valuable materials have been stripped from them, and multiple attempts have been
made to destroy them, but with the proximity of the surrounding city, and the thick concrete
walls, the demolition has proven too costly and difficult to undertake.
Of the 6 towers in Berlin only one remains mostly intact.
The Zoo Tower was destroyed by British engineers, but it didn’t go down without a fight.
On the first attempt the engineers packed it with 25 tonnes of dynamite, when the dust
cleared the Tower remained standing.
The tower finally collapsed on the third attempt with 35 tonnes of dynamite, and from there
the rubble was broken up and transported away, and the land handed over to the Berlin Zoo
where the hippopotamus park now resides.
Both of Hamburgs attack towers remain, with one being transformed into a nightclub and
the other now acting as a giant energy storage facility.
The thick concrete walls provide fantastic insulation, allowing the inside to be filled
with 2 million litres of water which is heated with biomethane and wood chip burners, solar
panels on the roof, and waste heat from a nearby factory.
Providing heating for three thousand homes and electricity for one thousand.
All of Vienna’s towers remain, but only one has been fully repurposed as an aquarium.
Once again taking advantage of the thermal stability of the interior for climate control
of the tanks, while the walls of the aquarium have been repurposed as a climbing wall.
The attack tower of Arenbergpark has been used as a storehouse for artwork too.
This attack tower in Augarten park had one attempted demolition, but it only managed
to crack in the roof and collapse one of the balconies,, and as a result the tower has
been reinforced with steel wire to protect the public from a possible collapse.
Today these towers remain as a gargantuan reminder of terrible war, but have been accepted
and assimilated into the urban landscape.
Parks have formed around them, zoos around and inside them, and even have been repurposed
to help towards a more sustainable future.
You may have admired some of the shots in this video, and I recorded all the footage
you saw of the Austrian Flak Towers myself, while on a road trip through Germany and Austria,
which you can follow by watching my latest vlog.
I’m the type of person that never reads instructions, I’d much rather dive in and
learn through trial and error, and that has led to some hilarious short comings with my
drone cinematography.
I only just recently discovered that I could adjust the pitch and exposure of the drones
camera in flight with small dials at the back.
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course on Skillshare.
I would have learned this lesson far sooner.
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As usual thanks for watching and thank you to all my Patreon supporters.
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