Teufelsberg (; German for Devil's Mountain) is a non-natural hill in Berlin, Germany, in the Grunewald locality of former West Berlin. It rises about above the surrounding Teltow plateau and 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 (Wehrtechnische Fakultät). 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 charges 5 to 10 euros for public access. History Teufelsberg is a non-natural hill, created in the 20 years following the Second World War by moving approximately of debris from Berlin. After the Communist putsch in the city parliament of Greater Berlin (for all four sectors of Berlin) in September 1948, separate parliaments and magistrates (; city government) were formed for East and West Berlin. This also ended much of the cooperation between West Berlin and the state of Brandenburg, surrounding West Berlin in the North, West and South. While part of the rubble from destroyed quarters in East Berlin was deposited outside the city boundary, all the debris from West Berlin had to be dumped within the western boundary. Due to the shortage of fuel in West Berlin, the rubble transport stopped during the Berlin Blockade. Although there are many similar man-made rubble mounds in Germany (see Schuttberg) and other war-torn cities of Europe, Teufelsberg is unique in that the never completed Nazi military-technical college (Wehrtechnische Fakultät) designed by Albert Speer is buried beneath. The Allies tried using explosives to demolish the school, but it was so sturdy that covering it with debris turned out to be easier. In June 1950 the West Berlin Magistrate decided to open a new rubble disposal on that site. The disposal was planned for . With the end of material shortages after the blockade, an average of 600 trucks deposited of material daily. On 14 November 1957, the ten millionth cubic metre arrived. The site was closed to dumping in 1972, leaving approximately of debris, and to a lesser extent construction waste. The Senate of (West) Berlin opted to plant greenery on the hill as a beautification project. Teufelsberg was originally thought to be high, which placed