Cherven

The stronghold of Cherven (Bulgarian, "red") was one of the Second Bulgarian Empire's primary military, administrative, economic and cultural centres between the 12th and the 14th century. The ruins of the fortress are located near the village of the same name 30 to 35 kilometres (19 to 22 mi) south of Rousse, northeastern Bulgaria.

Fort data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).