Humboldthain
On September 9, 1940 Captain von Below, Adjutant to the Führer writes a letter to Hermann Göring to transmit a Führesr order for the construction of anti-aircraft gun towers in Berlin . In this order there are various towers mentioned in different parks of Berlin. Amongst those three towers were to be erected in the Zoo and one tower each shall be constructed in Humboldthain, Friedrichshain and Tempelhof. Already on September 20, representatives of Air District, Anti-Aircraft Gun Artillery, Luftwaffe Staff Officers, Supreme Command of the Navy (OKM) as well as Albert Speer as a General Chief Building Inspector and Fritz Todt as minister for Ammunition and Armament meet in the Reichsluftfahrtministerium, the RLM (ministry of aeronautics ministry).
At this meeting the fundamental aspects of the bunker construction are discussed. Those present decide the four or octagonal form of the construction. Each corner should house a heavy gun. In 1940 the talk is of 10, 5 cm guns later at completion, 12.8 cm guns are installed instead into twin gun carriages. A fire control device is installed in the middle, 35 m far from the four gun positions. To fight low-flying aircraft 2 cm quadruplets and 3.7 cm guns are fixed on half-round balconies below the main battery.
The dimensions of these bunkers are enormous. The outer-wall thickness of the 35 m high giant is 2.6 m, that one of the end ceiling 3.8 m. Great value is attached to the strength. A self supporting corset which would not have impaired the complete static even at collapse of the walls arises within the construction. The concreting measures are so ingenious that one single cast takes place. The bonding of the concrete differently is prevented with that and increases the strength through this automatically. Per cubic metre of concrete one invests 50 kg of iron. The ammunition rooms are located on the ground floor of each of the four battle towers . Chain lifts transport shells and cartridges to the battle platform where they are protected by a 72 tons heavy armoured dome. The bunker measures 6 stories from the ground floor up to the battery. The 1st and 2nd floor serves the civilian population as a shelter, floor no 3 houses a hospital, offices or armament enterprises. The anti-aircraft gun garrison and other military staff are stationed in the 4th and 5th floors. Up to 18 000 people find shelter during the attacks. Three towers were realized in Berlin at long last: Zoo, Friedrichshain and Humboldthain. At the end of 1942 the anti-aircraft gun tower building programme is extended also to Hamburg and Vienna.
All three bunkers have one "smaller brother" each, the fire conducting tower. This calculates the necessary coefficients and transmits them via telephone line through a cable channel of 1.5 m of diameters to the battery. This cable channel is used in the case of Humboldthain during the final stages of the Battle for Berlin as an escape tunnel. The construction of Humboldthain starts in October 1941 and is completed six months later.
Dr. Wolfgang Waldhauer, called up as a grammar school pupil in Zwickau, like so many of his generation as anti-aircraft auxiliary, is committed to the service at a 2 cm quadruplet in the anti-aircraft gun bunker Humboldthain in January 1944. He reports of day attacks on March 4 and 6. A coloured B 17 crew member landed on the L tower with his parachute. The bunker itself is repeatedly hit by bombs on May 19, 1944. Among other things a quadruplet is wiped out with a direct hit. The garrison fortunately is at this time inside the bunker.
In the final stages of the battle around Berlin the anti-aircraft gun's tower also engage ground troops. The guns in the upper stories of the Brunnenstrasse fight Soviet tanks, the 2 cm guns shoot at Soviet marksmen in the upper floors of the Brunnenstraße.
After the end of the war he three anti-aircraft gun towers are blown up according to the directive no. 22 of the allied Kontrollrat. The French are more cautious as the northern part of the tower is located very closely to important train tracks. This is also the reason why this part is usable today.
The “Berliner Unterwelten” (Berlin Underground World) organization only recently manages to prove that a top secret laboratory for the radar research of electronic giant Telefunken was located in the cellar of the anti-aircraft gun tower Humboldthain. Reports of contemporary witnesses are confirmed definitely that they had seen "men in white coats" going into protected rooms.