Source: http://www.wieliczka-saltmine.com/about-the-mine/multimedia/photos

The Wieliczka Salt Mine is near Krakow, Poland. It was built in the 13th century and was mined for salt until recently. Now it is mostly a tourist attraction. It boasts the beautiful natural wonder of a salt mine with caverns and beautiful crystals, but also interesting man-made sculptures, statues, churches, altars, and bas-reliefs in the rock salt.