Fortress on peak Ostrets

A Thracian, ancient and late antique fortress rises on the dome-shaped Ostrets peak. A Thracian fortress was built on the summit in the 5th-3rd centuries BC, and in the 4th-5th centuries the fortress was rebuilt with new walls. Originally, the fortress wall was built of broken stones without solder joint; under the Thracians, the fortress was irregular in shape, and under the Romans - square.