I've been wanting to visit the Teufelsberg site for some time both for historical and photographic interest. After World War 2, the rubble from the ruined city of Berlin was moved and piled up to create the Teufelsberg or Devil's Mountain. Teufelsberg is unique in that the never completed Nazi military-technical college is buried beneath. The US National Security Agency built the listening station in 1963. The site was abandoned in the 1990s.
We visited the site by walking from Grunewald Station which takes around 30 minutes. Google maps is pretty essential due to the fact that the area is hidden by dense forest. Once at the top of the Teufelsberg we were greeted by a large group of men who appear to have inhabited the site and were keen to charge 8 Euros for entry after signing a disclaimer that basically said if we fell off anything or something fell on us they wouldn't be liable. It was clear anyone who tried to enter the site without paying would face serious resistance! Anyone visiting the site needs to understand that they do so at their own risk as there is a lot of broken glass lying around, unlit pitch black concrete stairways and many other risks associated with visiting an abandoned site.
Once in it's a Photographer's dream with lots of Graffiti and spaces to explore. Although little remains of the buildings original contents, the site is still a fascinating atmospheric wander through Berlin's recent past.
The interior of the building is covered in Graffiti, mostly political. It's clear that the site has hosted quite a few unauthorised parties!
There's lots of alternative art lying around whilst you can enjoy a decent coffee from a pop up kiosk and even a beer at the bar which is located next to the entrance.