This once valuable source of mercury has not been in use for almost a century and is nowadays opened for guided tours. The mine was first exploited in the 16th century and was used intensively for some four hundred years. There are several disused entrances to the mine, along all of which visitors can see stones containing small amounts of cinnabar, the ore from which mercury is extracted. Only one entrance is accessible, which leads to a 300m deep horizontal shaft and ends in an impressive limestone room inhabited by bats. Along the way the path passes by many newly formed stalactites and little creepie crawlies like spiders and grasshoppers, who have adapted to a world without daylight. The guided tour takes you to the heart of this eerie environment and is not for the squeamish. Contact the tourist office in the town to make arrangements.