Teufelsberg (German for Devil’s Mountain) is a man-made hill in Berlin, Germany, in the Grunewald locality of former West Berlin. It rises about 80 metres (260 ft) above the surrounding Teltow plateau and 120.1 metres (394 ft) above the sea level, in the north of Berlin’s Grunewald Forest. The hill is made of rubble, and covers an under-construction Nazi military-technical college (Wehrtechnische Fakultät). During the Cold War, there was a U.S. listening station on the hill, Field Station Berlin.
After the German reunification plans were to build luxury apartments, a hotel, a museum and a restaurant at the top of the hill. The project was scrapped after protests from the locals. The listening station is now a graffiti heaven.
More at Wikipedia.