Cherven was one of the Second Bulgarian Empire's primary military, administrative, economic and cultural centres between the 12th and the 14th century. The town was a successor to an earlier Byzantine fortress of the 6th century, but the area has been inhabited since the arrival of the Thracians. Cherven was first mentioned in the 11th century in an Old Bulgarian apocryphal chronicle. It gained importance after 1235, when it became the seat of the medieval Bulgarian Orthodox Bishopric of Cherven.
During the second half of the 14th century, the stronghold's area exceeded 1 square kilometre and had intensive urban development, including a fortified inner city on vast rock ground in one of the Cherni Lom river's bends, and an outer city at the foot of the rocks and on the neighbouring hills. The town had a complex fortification system and was completely built up. Cherven grew to become a centre of craftsmanship in the 14th century, with iron extraction, ironworking, goldsmithing, construction and arts being well developed. The town was an important junction of roads from the Danube to the country's interior, which also made the town a key centre of trade.
Cherven was conquered by the Ottoman Turks in 1388 during the Bulgarian-Ottoman Wars, initially retaining its administrative functions but later declining in importance.
A large feudal palace with fortified walls reaching up to 3 metres wide, two well-preserved underground water supply passages, 13 churches, administrative and residential buildings, workshops and streets have been excavated. The three-storey tower, 12 metres high, from the 14th century has also been fully preserved and was even used as a model for the reconstruction of Baldwin's Tower in Tsarevets, Veliko Tarnovo, in 1930. The site has been a national archaeological reserve since 1965 and is a popular tourist attraction.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.