Berliner Unterwelten (Berlin Underworld), 105 Brunnenstraße, Berlin, Germany

A visit to Berlin’s underworld is a strange and unsettling experience, where visitors enter a dark bunker and explore stairways and rubble taking them down under the ground. Take a tour to visit an air raid bunker, abandoned subway stations and tunnels used in World War II to smuggle people out of East Germany. There are four floors, where bomb and ammunition storage and a pneumatic postal system can be viewed.