The Belogradchik Fortress is a large fortress on the northern slope of the Balkan Mountains in Bulgaria.
The fortress walls are 2 m thick at the base and 12 m high. Three separately fortified parts are connected to each other by gates.
The first fortress on this site was built during the Roman Empire. The surrounding Belogradchik rocks served as a natural defense, so the walls had to be built only from the northwest and southeast.