Mining in Bochnia dates back to 1248 and was run by the Royal Family. The period of greatest expansion was the 15th and 16th centuries and, by then, five shafts had been sunk. The mine came under Austro-Hungarian control from 1771 to 1918. Back in Polish hands, output reduced but the site was decalred a historic monument in 1981.
Tourism in volume started in the 1980s and several tourist routes operate, incuiding one which involves an underground ferry crossing. It is also possible to stay overnight in the mine where the poure air is believed to have an impact on respiratory conditions such as asthma.
The site is on the UNESCO World Heritage list, alomgside its better-known neighbour Wieliczka. Details of opening hours and tickets are available here.