The Bükk National Park provides protection since 1977 for the fauna, flora, geological and cultural heritages of the area. The Bükk-mountains comprise an area of 43129 hectares covered largely by forests with a strictly protected area totalling 5677,4 hectares. The Bükk-mountains have the highest average height of all Hungarian mountains, its limestone peaks elevate over 900 meters. The mountain has variety of microclimates and surface geological formations, sheltering a rich fauna and flora. Mediterranean, alpine, and relic species from the Ice-Age can be found here, too. The fauna of butterflies and insects is unique. Over 90 bird species breed in the area, with many endangered species threatened by extinction, which have their last habitat in Hungary only in the forests and rock-walls of the Bükk-mountains. There are over 1000 known caves below the surface, many of them bear the treasures of stalactite/stalagmites. The Szent István- and Anna-caves at Lillafüred make this underground world accessible to the public.