From 12th - 13th century, smaller than Wieliczka's one, but not less interesting. Sometimes called an underground town because of its size. Chambers measure 4.5 kilometres in length at 16 different levels. One of the chambers was converted into a sanatorium and you can spend a night there inhaling salt. There is also a restaurant supposedly located lowermost in the world. Like the Wieliczka salt mine, it's inscribed on the UNESCO World Heritage list.