Teufelsberg Radar Station (Germany)
During the Cold War, the U.S. National Security Agency (NSA) built a man-made hill and called it Devil’s Mountain, or Teufelsberg in German. On the mountain, the US built a radar station – part of the NSA which was forming global Listening Stations to eavesdrop and spy, intercepting Soviet, East German and other countries’ communications. It was also rumored to be part of the ECHELON intelligence gathering network.
The Listening Station closed in 1994 and was since used as air traffic control then the site was privately bought but has never been developed.