The ruins of the castle in Visegrad is located north of the village of the same name, 5 kilometers southeast of the town of Kardzhali, where the Thracian fortress. The name of the castle is of Slavic origin and means "high town". The same name has repeatedly been used to name some of the forts of the Slavic states. Among the local population, it is known for the place name "Hisar Yustyu" ("Mountain Fortress").

The fortress is located on top of the "Harman Stone." From the east, south and west it is almost impregnable. The northern side is protected by a fortress wall curved shape, extending from the western side.

During archaeological excavations in 1971 and 1974 were identified and subjected to conservation of the city wall and the inside of the Visegrad castle. The fortress wall reaches about two meters wide and one meter in height. At its construction were used rough stones and a special bonding solution, in some places, the joints are filled with stones small stones and earth. Entrance to the fort is located on the east side and is about two meters wide.

In the courtyard of archaeologists found a small dugout and keep the furnace base. The excavations also found many traces of life settlers: pottery, millstones, iron tools and weapons, and others. The oldest samples date back to the late Bronze Age and Iron Age. Scientists suggest that this place was inhabited since ancient times to the Middle Ages.

Nearby it was also found another 17 mounds of Thracian burial.