The hill is made of debris and rubble, and covers an unfinished Nazi military-technical college (Wehrtechnische Fakultät).

The site of the former field station is now fenced off and is currently being managed by an organisation which charges 10 euros for public access.

[2] 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.

[3] New measurements show that Teufelsberg is actually 120.1 metres (394 ft) high,[4][5] making it higher than Großer Müggelberg.

The US National Security Agency (NSA) built one of its largest listening stations atop the hill in 1963, supposedly as part of the global ECHELON intelligence gathering network.

This discovery eventually led to a large structure being built atop the hill, which would come to be run by the NSA (National Security Agency).

During the NSA operations some other curious things happened: It was noticed that during certain seasons the reception of radio signals was better than during the rest of the year.

While there were rumors that the Americans had excavated a shaft down into the ruins beneath, that was never proven, and was likely based on reports that those who maintained equipment in one of the first enclosed antenna structures accessed the upper levels of the inflated dome via an airlock that led to a "tunnel" that was embedded in the structure's central column.

Speculation as to what might have existed within the highly restricted area frequently gave rise to rather elaborate but false rumors; one theory stated that "the tunnel" was an underground escape route, another that it housed a submarine base.

As of April 2017, entry to the site is €8 payable at the main entrance gate and a sign informs visitors that it is open from 10am to "one hour before sunset."

Following the announcement of plans to raze the facility and reforest the hill,[13] talk of preserving the facility resurfaced in 2009, spearheaded by the Field Station Berlin Veterans Group, which hopes to have the memorial named in honor of Major Arthur D. Nicholson, the last military Cold War casualty, the U.S. Military Liaison Mission tour officer who was shot and killed by a Russian sentry near Ludwigslust on March 24, 1985.