At the end of the Second World War, Berlin had over 400,000 homes destroyed and an estimated 75 million cubic meters of rubble that needed to be cleared. The rubble from destroyed buildings were dumped mostly outside city boundaries but some of the dumping sites were within the city. As many as eight such debris mountains, known as Schuttberge, are known to exist within Berlin which have since become part of the city’s landscape. The tallest of these and the one with the most interesting history is Teufelsberg, or the Devil’s Mountain, located in the Grunewald locality in the western parts of Berlin.

Teufelsberg is 80 meters tall and is made of 26 million cubic meters of rubble. It sits on the site of a former Nazi military training school designed by Hitler’s chief architect Albert Speer. In fact, the ruins of the school are still buried underneath. After the Allies won the war, they tried to demolish the school using explosives, but the structure was so sturdy they decided that it would be easier to bury it under rubble instead.

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Everyday up to 800 trucks would arrive and dump 7,000 cubic meters of rubble at Teufelsberg. The rubble were collected and sorted mostly by the women, because after the war, with 15 million men dead, missing or wounded, the responsibility of cleaning up and rebuilding Germany fell largely upon the womenfolk. These women came to be known as Trümmerfrauen or ‘rubble women’ for their efforts.

Although Teufelsberg was used as dumping ground until 1972, the hill had achieved its final shape and height by the end of the 1950s. At 80 meters tall above the surrounding and 120 meters above sea level, Teufelsberg had become the highest point in Berlin. The unobstructed view that the summit commanded across all directions made the US Army realize that the hill would become an excellent place to set up a listening post.

At first mobile listening units were deployed at Teufelsberg to listen into communications from Russian-controlled East Germany. In 1963, permanent structures were erected. It wasn't very discreet. There were five large radar domes, some of them perched atop three and six-story towers. Each radar dome contained massive 12-meter satellite antennas and the most sophisticated spying equipment for the time, enabling the US and British intelligence to intercept satellite signals, radio waves, microwave links and other transmissions.

Allies referred to Field Station Berlin as “The Hill”, but locals preferred to call the main listening tower and radomes "Berlin's Balls". Photo credit: Axel Mauruszat/Wikimedia

Operated by the US National Security Agency (NSA), and rumored to be part of the global ECHELON intelligence gathering network, Field Station Berlin —as it was officially called— became one of the largest listening stations. The facility’s existence wasn’t a secret but highly restricted, giving rise to elaborate rumors such as the existence of a secret tunnel from the hill that served as an escape route or to a submarine base.

Situated high above all obstructions, the Teufelsberg enjoyed excellent reception in most radio bands. Radio reception even mysteriously improved, to NSA’s surprise, during certain times of the year. It was eventually figured out that the Ferris wheel erected during the annual German-American Volksfest Festival functioned as an excellent resonator. The NSA talked the festival organizers into keeping the wheel in place long after the festival was over.

After the fall of the Berlin Wall and end of the Cold War, the facility was abandoned in 1992. In 1996, the 4.7-hectare site was sold to a private developer who planned to construct a hotel and a spy museum, but the project never took off.

Teufelsberg is currently used as a recreational area. Berliners meet here in the summer for picnic, kite flying, paragliding and mountain biking. In winter, the hill becomes just right for sledging and snow boarding. The facility itself is slowly crumbling away. Thieves and vandals have stripped the site of any valuable materials that remained after the spies left. All available surface is covered with graffiti.

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Sources: Wikipedia / Abandoned Berlin