Wikipedia
Heimkehle
The Heimkehle is one of two great gypsum caves in Germany that are accessible as show caves. It lies on the southern edge of the Harz Mountains between Rottleberode and Uftrungen, east of Nordhausen, right on the state border between Thuringia and Saxony-Anhalt. The cave may be visited as part of a 45 minute long guided tour.