Smalyany Castle was probably built before 1626 by the order of Duke S. A. Sangushka. It took part to the several battles in the war with Russia (1654-1667) and in Great Northern War (1700-1721). The castle consisted of inner court and 3-4 corner towers. They buildings had three storeys. The decline of Smalyany castle began in the mid-18th century. Today ruins with embossed decorum have survived.
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.