The fortress was built in the place of a Byzantine fortress from the sixth century. It served as an important centre during the Second Bulgarian empire, second only to the capital of Turnovo. It minted coins and in 1235 it became the seat of the Bishopric of Cherven.
The fortress was burned by the invading ottomans in 1388, with most people fleeing to what is today Ruse.
There is also a 3D reconstruction of the town during the 14th century
Wow, very cool, thanks for all the extra info too!