I’ve been on holiday for the past 2 weeks with visitors. Done sooooooo much touristy stuff in Berlin it’s been crazy.
First off was Teufelsberg the abandoned American spy station on top of a man made mountain in Grunewald Forest in West Berlin. I read a lot about it before I went. Turns out it was an old Nazi Military training academy but was so well built when the war was over the allies tried to blow it up and couldn’t destroy it so they took the ruble from all the bombings and broken buildings from the streets of Berlin and piled it on top fo the training facility, making a mountain which now has trees and lots of nature growing on it. During the Cold War the Americans built a listening post on top of the mountain to try and spy / listen in on the Soviets. After the wall came down it was abandoned and is now a place for urban exploration and amateur photographers. It’s well worth a visit, though you have to crawl through a hole in the fence and it is technically “trespassing” it’s really amazing and has the best views of Berlin that I have seen.