NSA Field Station Teufelsberg - a late post mortem

The NSA Field Station Berlin Teufelsberg was one of the premier listening posts of the cold war. Situated on top of the highest elevation in West Berlin - the Teufelsberg, the station had unobstructed reception of signals from all directions. And viewed from West Berlin, in all directions was "East". Situated on an artificial hill near a string of lakes, the Teufelsberg enjoyed excellent reception in most radio bands that were otherwise difficult to receive at long distances. The NSA got so far in their search for better reception, that they prolonged the operation of a flywheel that was accidentally found to be a excellent resonator for certain radar installations deep in the east. (more)