During the Middle Ages, a castle of the ruler of Perperikon was built upon the ruins of a Roman structure.
A tall defensive tower of the donjon type belonged to it. It is octagonal in shape and is believed to have reached a height of 15–18 meters.
Today, the tower is preserved up to about 7.80 meters, with three distinct levels clearly visible.
It is assumed to have been built in the 13th century, when Perperikon was within the borders of the Bulgarian Tsardom. A medieval seal was also discovered, featuring a silver-gilt plate depicting Tsar Ivan Alexander.
