Kletno was an area of mining for iron, lead, silver and copper from the thirteenth century. After the Second World War, due to the need of the Soviet Union for uranium to make atomic bombs, a search began resources. Uranium ore was mined at Kletno from 1948 to 1953. The mine had 3 shafts connected to 37 kilometres of tunnels. Large quantities of waste were produced for a very small amount of uranium – just 20 tons in total. Heavy machinery was used in wide tunnels. Visitors can go into one for around 200 metres. The mine is most popular for its colourful minerals: the walls show veins of fluoride, fluorspar, amethyst, malachite and quartz among others. There are also displays of equipment, maps and lamps that tell the story of mining in the area from the Middle Ages onwards.