The Baradla Cave System is the Hungarian part of the 25-kilometre-long Baradla-Domica Cave System, the largest subterranean hydrological system of the karst plateau in Hungary and Slovakia. The Site is characterized by a permanent subterranean stream, ponds, rich dripstone formations, and diverse species representative of subsurface fauna as well as rich archaeological remains. The extended underground world of the Aggtelek and Slovak Karst provides a habitat for more than 500 species of troglobite, troglophile and trogloxene animals, including endemic species such as the beetle Duvalius hungaricus and earthworm Allolobophora mozsaryorum. The Site also includes habitats of community interest such as wet meadows and humid grasslands, which support a number of threatened species of plants and animals. The sediment of the cave system plays an important role in the filtration of heavy metal pollution. The most important archaeological sites are the settlements of Bükk culture both inside and in front of the cave entrance, with charcoal drawings unique in Central Europe. More than 100,000 tourists visit the Site annually, for whom tours and study trails, as well as hotels and campsites, are available. Threats affecting the ecological character of the Site relate to forestry and pollution from wastewater and domestic waste.