The late-antique and medieval castle Kaleto

The late-antique and medieval castle near the village of Koshnitsa (Smolyan region) is situated on conical peak of marble limestone (1006 m), which is pierced by a cave in north-south direction. The fortress and the peak can be reached going through the cave only. There is evidence that the site was used as a sanctuary, and transformed into a fort in early Chalcolithic period (V-IV century BC). 

The castle has existed since Byzantine times and it goal was to guard the route of the Central trans-rhodopean route in the Middle Rhodopes.