Teufelsberg is a non-natural hill in Berlin, Germany, in the Grunewald locality of former West Berlin. It rises about 80 metres above the surrounding Teltow plateau and 120.1 metres above the sea level, in the north of Berlin's Grunewald Forest. It was named after the Teufelssee (Devil's Lake) in its southerly vicinity. The hill is made of debris and rubble, and covers an unfinished Nazi military-technical college. During the Cold War, there was a U.S. listening station on the hill, Field Station Berlin. The site of the former field station is now fenced off and is currently being managed by an organisation which is the author of the graffiti all over the place.