"Bärenhöhle Schwäbische Alb" (Germany)

Based on the fact that the Swabian Highlands are made of karst there are a lot of caves. Near Sonnenbuehl is one of these caves called "Bärenhöhle"  (bear's den) situated. Inside there are a lot of very beautiful  stalactites and stalagmites. The cave was developed in the 19th century. Today the cave can only be visited in summer, in winter it belongs to the bats doing their winter sleep. Of course there are some remains of the further inhabitants, the cave bears, which has been extinct in the last Ice Age.