On this picture I’m at front of the remaining of the Berlin’s wall. The building in the background is a remaining of Gestapo-zentrale (Gestapo headquarter) the main Gestapo building itself was destroyed apparently during WW2

When I was in Berlin, I went to Float-Berlin.de they offer floatation tank. Floatation tank are supposed to offer you sensory deprivation while you float on water in a capsule or tank (water is mixed with a certain type of salt to make you float).
It offers great and quick deep relaxation. It also helps your brain to produce theta brainwaves while awake.
My floatation tank was the Samadhi tank that you can see in this video. I made the video right before going in the tank.
The nice music you can hear was the music I heard while I was relaxing in the tank going through a series of emotional release and meditations.

This particular tank had blinking stars in the dark. So it was even a more beautiful experience. It was like looking at stars in the sky during the night.