The Null Stern ("Zero Star") Hotel occupies a subterranean Swiss air raid shelter outside Zurich, which has served little purpose since the Cold War. Few updates were made to the place in order to ready it for guests. It costs less than a room at a Motel 6 (around $25/night), and you certainly get what you pay for: Rooms are arranged dormitory-style, with no walls between beds, a shared bath, and limited hot water. Rubber hot water bottles hang from laundry lines along the concrete wall to provide low-tech personal heat systems in the windowless bunker.
The concept was developed by a pair of brothers, Patrik and Frank Riklin, who run a studio called Atelier für Sonderaufgaben and clearly believe in the "no press is bad press" approach to building a high profile. After a night in the Null Stern without any sunlight or privacy, nobody could honestly say they felt rejuvenated, but as far as unique experiences go, this is one to write home about.