Devetàshka Cave, Bulgaria

Devetàshka cave (the name in Bulgarian: Devetàshka peshterà) is huge karst cave in Bulgaria, known for its long term occupancy for human and other type biological populations during extensive historical periods. It is also home to nearly 30,000 bats.
Devetashka cave is located 15 km (9.3 mi) northeast of Lovech and approximately 2 km (1.2 mi) from the village of Devetaki. To reach the cave one can walk along a narrow path by the river, starting from the village of Devetaki.