Flakturm und Luftschutz bunkers

In these limited articles I will try to cover in some detail the fascinating subject of Berlin’s bunker building history during world war two. These articles are not meant to be in anyway exhaustive, definitive or authoritive since this subject is just to large to cover in such small articles as these, however I will try to convey to the reader as much fact as I am comfortable with.

I think that it’s appropriate to start with the most famous bunker of them all the ‘Zoo Bunker’ or Tiergarten Flakturm, which represents the pinnacle of German concrete bunker building at any time during or even in some peoples opinion since the second world war.

Because the Tiergarten flak-towers were built beside the Zoological gardens (Zoologischer-Garten) to the west of the government district it quickly and hardly surprisingly became known to all the Berliners as the ‘Zoo bunker’ and housed the 1st Flak Division who controlled the four twin mounted 128mm Flak Guns for offensive operations.

Quite often when most people think of bunkers they imagine an underground structure buried in the earth, which is true with an average bunker say on the west wall or with the French Maginot line, however the Third Reich together with architect Prof Friedrich Tamms and with the aid of Organisation Todt took bunker construction to new never imagined levels when they created the three massive flak towers ringing the city of Berlin as part of the air defence network designed to protect the city from allied bombing. The first aspect of flak tower construction we need to address is the fact that they were always built in pairs, a Gun-tower and the Command-tower, both normally sited close together between 350-500 meters and linked via underground cables. The purpose of the Command-tower often referred to as the ‘L-tower’ was to relay targeting information gathered using such equipment as the FuSE 65 ‘Wurzburg Giant’ radar, FuMG 39T Mammheim radar and the R43 10 meter range finder all mounted on the roof top. This information was processed and communicated to G-tower command post located centrally on the roof top and distributed to the four large corner tower mounted Flak 44 128mm twin mounted flak guns.

The Tiergarten flak-towers or 'Zoo bunker'

One the four large corner tower mounted Flak
44 128mm twin mounted flak guns

These highly effective ‘Hanomag’ built weapons had a range up to a height of 15,000 meters, but due to these Flak guns being difficult and costly to produce they were not ready for installation on the completed Gun-towers as in the case of the Zoo bunker till Sept 1942, during this interim period 105mm flak guns were fitted until the delayed 128mm flak gun were ready to be lifted and mounted in position. This was also a problem that the other Flak towers encountered.

 All three pairs of towers were fitted on there lower platforms with various light flak guns generally of the 20mm and 37mm calibre range, primarily for offensive operations that could engage small low flying allied aircraft. All the weapon systems on both flak towers are also capable of fulfilling a defensive role against both ground and airborne targets.

The three flak towers were situated to form a triangular defensive ring around the Berlin city centre which encompasses the government district, and thus were sited in the park land of the Tiergarten to the west of the city [designated as Flakturm I], Friedrichstain in the east [designated as Flakturm II] and the Hunboldthain park in an area to the north [designated as Flakturm III].

The photo below gives us a view across the roof top of the Zoo Gun-tower to the Zoo Command-tower some 400 meters away: note the 105mm Flak guns still fitted and the Victory Column standing in the Tiergarten in the distant back ground.

On top of the Tiergarten flak tower.

The Tiergarten flak tower (Zoo Bunker) was the first of the three to have its construction completed in April 1941. The Zoo bunker Gun-Tower measured some 70x70 meters and 39 meters tall with a wall thickness of 2.5 meters at ground level and tapering too 2 meters towards the top with its ceiling measuring some 3.5 meters thick. The inside of the structure contained one cellar, ground floor and five upper floors, several stairwells including one for each corner tower and two freight elevators to handle the large and heavy 128mm ammunition shells. The Command-tower outer dimensions measured 50x23 meters and 39 meters tall, the interior construction and dimensions are much the same as the G-Tower.

It’s worth noting that all these Bunkers were constructed to be self-sufficient with their own independent water reservoir and diesel generators for production of their own electrical power supply.

All threes pairs of towers are built virtually to the same design and specification with an average cost for each pair of towers estimated at somewhere between 80-90 million Reichmarks. However there were some minor exterior detail changes made for each pair, this is very helpful to us for visual identification from period photographs, the most obvious differences concern the lower platform with the Zoo bunker having swallows nests on each of the twelve corners were as the Hunboldthain tower omitted these in favour of clipped corners, however the Friedrichstain towers retained these swallow nest found on the Zoo bunker, but changed the design of the upper roof top command post to a squared concrete wall design rather than the circular design on the Zoo bunker G-tower, this design feature is also found on the Hunboldthain G-tower.

The Friedrichstain flak towers construction started in April 1941 and only took some 6-7 months to build. From this period photograph we can see the flak tower fitted with 105mm flak guns indicating that this picture was taken around summer 1942. The Command-tower can be just seen to the right of the picture.

The Friedrichstain flak tower.

The Hunboldthain Flak towers construction was finished in April 1942, however as already mentioned 105 mm Flak guns had to be fitted for operations till the 128mm twin mounted guns were ready in late 1943. The command-tower was built next to Gustav-Meyer-Allee, across this road is an AEG plant seen here in the photograph directly behind the Command-tower, and was concerned with the heavy steel industry, The AEG plant was heavily damaged in the fighting as a short walk around will soon reveal the many shell and bullet holes on the outer building walls, note that the top of each corner tower on the main assembly hall have been completely re-built.

These flak towers were designed to serve several other purposes for the city of Berlin, Chiefly as shelters for the civilian population during allied air raids, originally they were intended to hold some 9000 individuals, however as the ferocity of the war progressed there was on occasions reportedly up to 30,000 civilians taking shelter. These flak towers were also designed to house important art treasures for the city, whose museums were under constant attack day and night by the allies, also in the case of the Zoo bunker, a hospital with up to 95 beds, two operating rooms and all the necessary nursing staff was located on the third upper floor.

By the closing stages of the war all three flak towers had took direct hits from allied planes with no major damage to report. What’s more with the Russian encirclement in 1945 they suffered over ‘open-sights’ artillery fire! But none of the Russian shells were successful in penetrating the outer concrete walls. With the Zoo bunker surrounded and being fired upon point blank, it wasn’t long before the occupants surrendered to the Soviets that time came at 12.30 am 2nd May. For the Hunboldthain and Friedrichstrain Flak towers surrender came on the 3rd May 1945.

After 1945

The Zoo Gun-tower ‘Zoo bunker’ was completely demolish by the British between 1947 and 1948. The remaining bunker rubble was completely erased over the next few years so that by the late 1950’s nothing remained; now the Berlin Zoo has extended its complex over the area. As for the Command-tower this too was completely demolished by the British over the same period and most of the concrete was removed, however a small hill remains on this location which has had a large ditch dug on the south side to create an island in the Tiergarten park land.

Both the Friedrichstain Gun and Command towers were blown up after the war, however to remove the concrete rubble is a costly business, so in an effort to landscape the park, spoil was heaped over the remains and planted with tree’s to create what is referred to today by Berliners as ‘Bunker hills’. Now these towers are almost completely invisible and the trees on all sites are mature.

Because the location of the Hunboldthain Gun-tower was next to a main U & S-bahn line, demolition was limited to the south side only and spoil was heaped up on this side leaving the north side to this day partly exposed. The Command-tower was also demolished and landscaped into a ‘bunker hill’. Covered with mature trees only the very top now remains visible.

The post war demolition gets underway.

Hunboldthain Gun-tower after the demolition phase was completed. All that remains now is for spoil to be heaped up on the collapsed south side and trees planted.

Northern face of the Hunboldthain Gun-tower as can be seen to day, Rock climbers use this face as a practice Matterhorn, and has been sprayed with concrete for there use, however on close inspection war damage is still very much evident.


Rock climbers at the Northern face of the Hunboldthain Gun-tower.

All that remains today of the Hunboldthain Command-tower, with the rest being buried under spoil and covered with mature trees to create a large hill. Beware as some of these bunker hills are very steep to climb and believe it or not with some fifty years of growth around them they can be difficult to locate within these Berlin Volks parks.

In the continuing part we shall take a look other Flak towers in Germany and cover air-raid shelters known as Luftschutz-bunkers, specifically designed to protect the civilian population of Berlin.

Contributed by Simon Garner.

Copyright© of Grossdeutschland 2008.