The Mezek Fortress, 6.5 decares (6,500 square metres) in area, is claimed to be among the best preserved Bulgarian medieval castles. It dates to the 11th century. Along with the Thracian tombs, it was studied by a team under archaeologist Bogdan Filov in 1931–1932. The castle has nine towers, five of which lie at the vulnerable south wall. The Mezek Fortress was built out of stone, with two decorative lines of bricks on the outside. It suffered some destruction around 1900, when stones from the fortress were used for the construction of Ottoman barracks in Svilengrad.
Source: Wikipedia
