Old mine, located near the village of Golak, Kostenets. It offers excellent living conditions for bats that form colonies here.
This cave is one of the few natural habitats in which protected bat colonies. The cave is inhabited by Common bent-wing bat (Miniopterus schreibersi),
Long-fingered bat (Myotis capaccinii), Greater mouse-eared bat (Myotis myotis), Lesser mouse-eared bat (Myotis blythii), Greater horseshoe bat (Rhinolophus ferrumequinum), Lesser horseshoe bat (Rhinolophus hipposideros), Nathusius’s pipistrelle (Pipistrellus nathusii) and Parti-coloured bat (Vespertilio murinus).