The foundation of Tešanj Castle was started even before the Romans conquered the region. Exact dates are unknown. It was later enhanced by the Romans, Slavs and the Ottoman forces. It has been primarily a defensive fortification. Tešanj Castle is one of the most significant and biggest castles in Bosnia, with an area of 6,296 square metres. During the Ottoman period, the destroyed castle was rebuilt castle and it had a permanent garrison.
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.