The Volkspark Humboldthain is a public park located in Gesundbrunnen part of the Mitte borough.
The construction of the original park started in 1869, the 100th birthday of Alexander von Humboldt, and construction was finished in 1876.
During the 2nd world war the looks of the park changed heavily with the construction of two huge Flag towers. Other flag towers were constructed in Zoologisher garten and Volkspark Friedrichshain.
These bunkers housed huge anti aircraft guns, but were also constructed to protect the people in case of an attack.
After the war only one of the two towers could be demolished, because the other was located to close to the S-bahn track.
The destroyed part of the bunkers was covered by rubble from the ruins of destroyed buildings. With the passage of time and the growth of greenery, the hills now appear to be completely natural features.
The part of the tower that was not destroyed is in use as a lookout point.
The interior of the bunker is open to the public. The people from Berliner Unterwelten give daily guided tours through this bunker, but also through many other buildings, bunkers and u-bahn stations around the city