The abandoned spy station at Teufelsberg, Berlin is on top of Devil’s Mountain rising up from the Grünewald forest. This man-made hill was constructed from millions of cubic metres of rubble created by bombing raids and artillery bombardments during World War II. The remarkable acoustics is in the almost spherical radome on top of the highest derelict tower. These domes used to cover listening equipment used by the British and Americans to spy on the East. There are a number of different sounds effects you can play with in the dome. Climb on top of the concrete plinth and get into the middle of the sphere and the strong focus creates richocheting sounds when you clap your hands.
Alternatively, you can try whispering just off-centre, and see if you can find the right spot for whispering into one of your own ears. If you go to the side of the dome and a friend goes to the opposite side, you can use the walls as a whispering gallery. Whisper into the wall and your voice will skim the inside of the walls and your friend will hear your words apparently emerging from the graffitied walls. If instead of whispering quietly you make a loud bang near a wall, then you can hear the bang pass you several times as it does complete circuits of the dome walls. This sound example has three balloon bursts:
Being reverberant, the dome also attracts musicians to play music.