During the last 3 years i´ve been to the Teufelsberg a few times. If you´re up to adventures i can warmly recommend this magic place. You will definately experience the most wonderful view over the city if you dare to slip through holes in fences, climb hundrets of stairs in total darkness and don´t mind getting your shoes dirty.
Go to the trainstation “Grunewald” (S-Bahn) and by looking on the map in the beginning of the forrest next to the station you will find your way. Preferably when the sun is setting of course… 🙂 and HURRY!! I´m afraid they might shut it down one day.
Teufelsberg certainly is on my list of places to visit after a co-worker told me how it was “built” over almost 20 years. Is it guarded in any way (not that it would keep me away ^^)?
Bet you’ve been to Grabowsee (30 minutes by foot from KZ Sachsenhausen in Oranienburg) and the Spreepark am Plänterwald as well, right? If not you definitely should. First has decayed quite well and is full of more or less alternative artworks and sculptures while the second has an amazing mixture of joy and melancholy.