NSA Listening Station
The National Security Agency listening station is located on a 80 metre hill called Teufelsberg, which translates from German to 'evils Mountain' and it itself has a fascinating history. In 1937 Hitler himself started the construction of a Military Technical Facility designed by the architect Albert Speer, due to the war the buildings were never finished but were apparently so strongly built that it was almost impossible to destroy them, so the Allies took the decision that all of the building that had fallen in Berlin during the War because of bombing raids should be razed to the ground and the rubble deposited on top of the facility, some 400,000
homes ended up here and the rubble was turned into a hill which is now the highest Hill in Berlin. After the war a lot of displaced people lived around the hill digging into the ruins for valuable things to sell! In 1960 a small skiing centre started on the hill with ski lifts taking you to the top (I could have done with that when I went!)
Teufelsberg was located in the British sector of Berlin, but the land on the hill was lent to the Americans in 1963 so that they could install a listening station to try to overhear what was being said on the "other side". The ski lifts were removed as it 
was found that they interfered with communications. The main interest for anyone going to the listening station is the "golf Ball" that sit a top of the main building, there are 3 left in total, 2 on the roof and another one higher up accessible by a concrete staircase, 270 steps in total and yes you do feel it!! The domes themselves are now empty but they echo very well especially the top one.
In 1989 - 1990 with the unification of Germany and the fall of the Berlin wall, the need to spy on the communications of the other side was no longer needed and
the base was closed. Berliners wanted the hill to be returned to them for their use but in 1996 the base itself was sold to a group of developers who wanted to build exclusive apartments on the hill, but the decline in the need for housing halted the plans and the Listening station now stands empty.