Wieliczka salt mine, near Krakow, Poland.
The Wieliczka salt mine reaches a depth of 327 metres (1,073 ft) and is over 300 kilometres (190 mi) long. The rock salt is naturally gray in various shades, resembling unpolished granite rather than the white or crystalline look that many visitors may expect. During World War II, the shafts were used by the occupying Germans as an ad-hoc facility for various war-related industries. The mine features an underground lake; and the new exhibits on the history of salt mining, as well as a 3.5 kilometres (2.2 mi) touring route (less than 1% of the length of the mine's passages) that includes historic statues and mythical figures carved out of rock salt in distant past. More recent sculptures have been fashioned by contemporary artists.
The Wieliczka mine is often referred to as "the Underground Salt Cathedral of Poland." In 1978 it was placed on the original UNESCO list of the World Heritage Sites. Even the crystals of the chandeliers are made from rock salt that has been dissolved and reconstituted to achieve a clear, glass-like appearance. It also houses a private rehabilitation and wellness complex.