Ustra

Ustra is a medieval fortress high in the eastern Rhodopes, built on a rocky summit above steep wooded slopes. Cliffs protect it on the north and west, while stone walls and towers enclose the more accessible sides. Archaeological finds suggest that it was established around the tenth century to guard a route through the mountains. Its towers contained several storeys joined by stone staircases, and buildings inside the walls provided shelter for the people who held this remote stronghold.