The Bochnia Salt Mine (Polish: Kopalnia soli Bochnia) in Bochnia, Poland, is one of the oldest salt mines in the world and is the oldest commercial company in Poland. The Bochnia salt mine was established in 1248 after salt had been discovered there in the 12th and 13th centuries, and became part of the royal mining company, Żupy krakowskie (Kraków Salt Works). In 1990, the mine ceased producing salt but remains a tourist attraction. In 1981 the Bochnia salt mine was declared a heritage monument. It is one of Poland's official national Historic Monuments (Pomnik historii), as designated on 6 October 2000, and is overseen by the National Heritage Board of Poland. The chapel in the mine has train tracks running through it. History The mine shafts measure 4.5 kilometres (2.8 mi) in length at about 330–468 metres (1,083–1,535 ft) in depth below the surface, at 16 levels. In 2013, the mine was added to the UNESCO World Heritage List as an extension of the Wieliczka Salt Mine inscription of 1978. August Passage The August Passage is the...