The Devetashka cave is located 18 km north-east of Lovech and 2 km away from the village of Devetaki.
The cave is also known as Maarata or Oknata (“the windows”) due to the seven holes of different size in the ceiling, through which light enters and illuminates the central hall and parts of its two branches.
The Devetashka cave is one of the three most significant subterranean habitats of bats in Europe. Currently there are 45 known animal species within it. This number does not include several species of birds, such as owl, tawny owl, Eurasian crag martin, pallid swift, black redstart, which make their nests in the cliffs around the entrance. Three of the mentioned 45 species are troglobionts: the woodlouse Trichoniscus tenebrarum, the cave-dwelling relative of the caddisflies Niphargus bureshi and the Myriapod Lithobius tiasnatensis. Twenty-one species are the troglophiles, including 11 species of bats. The remaining 21 species are trogloxenes.
The Devetashka cave is a unique natural and cultural phenomenon. The good life conditions have attracted the attention of man since most ancient times. The close proximity of the Osum river, the abundance of forests, pastures and fertile lands contributed to its habitation. The cave is a cultural monument and a protected site with national and international importance.
More considerable studies of the cave were conducted in the beginning of the 1950's, in relation to using it for storage purposes. The studies indicated that the Devetashka cave had been inhabited, with several interruptions, throughout all historical ages. The oldest traces of human presence dated back to middle of the Palaeolithic, at some point before 70000 BC. The Devetashka cave is among the cave dig sites with the richest cultural remains from the Neolithic era (6000 – 4000 BC).
The cave entrance is 35 m wide and 30 m high. About 40 m inside, the entrance widens, forming a wide chamber with an area of 2400 m2. The chamber's height is 60 m, reaching up to 100 m in places.
From the central chamber, about 200 m away from the entrance, the cave splits into two branches. The left branch is more than two kilometres long, with a small river flowing through it, passing through the central chamber and disgorges itself into the Osum river. The right branch is dry and warm. Its entrance is 2.5 m high and 5.70 m wide. It becomes wider as it goes deeper and forms a rectangular chamber – 50 m long and 10-15 m wide. This branch ends with a small gallery and a circular chamber known as the Altar.