The former HQ of the Stasi, East Germany's feared secret police service, has a troubling atmosphere. "Building 1" has been turned into a museum, where you will see exhibited, as they were at the time, the offices of Erich Mielke, who was at the head of the service, and his close associates. It's all there: microphones, miniature cameras, a cell. Since 2016, an open-air exhibition in front of the building traces the peaceful revolution that led to the fall of the Wall in 1989.