The remains of the late-antique and medieval castle Hasara are located 2.5 km southwest of the village of Tsar Asen (Pazardjik district) and 3 km east of the village of Sbor. The fortification was built on a not highly elevation and was with elliptical form - length of 90 m in East-West direction and width of 35 meters in the North-South direction. The entrance to the fortress was from the east. The northern part was naturally protected by high and steep rocks and the river of "Luda Yana" and therefore there has not been built а wall.
Today from the fortress are preserved small part from a fortress wall only.