 Since 1993, the Guinness Book of World Records has termed the "Feengrotten" "the most colorful cave grottoes in the world".The caverns consist of three chambers connected by galleries.In the first chamber, information is presented about the history of the mine — in the 16th to 19th centuries an alum shale mine that was closed in 1850 but opened for sightseeing in 1914.