Ceský Krumlov is an historic town of outstanding interest in South Bohemia, laid out around a castle of the late 13th century that towers above the Vltava river. A spectacular 5-level bridge of 1765 connects the castle with a monastery. The town was designated a UNESCO World Heritage Site in 1992, and has undergone extensive restoration since the ‘velvet revolution’. The area has a long tradition of mining, of gold and silver, but particularly of graphite, the crystallized form of carbon which is amongst the softest of minerals. It is used most obviously in the manufacture of pencils, but also as a dry lubricant, in polishes, for lining moulds in foundries, and in the manufacture of electrodes for furnaces used for melting metals. The first reference to graphite mining at Ceský Krumlov is in the year 1767. There was rapid expansion after 1846 with the formation of several new companies, and by the 1870s about a thousand people were mining graphite in the region. The industry contracted in the 20th century, and the last mine to work in the area is now a museum, where visitors, after donning protective clothing and boots and putting on helmets with lamps, are taken on a 2km train ride into the workings, before exploring other parts of the mine on foot.