The remains of the château de Bar-sur-Seine are the ruins of a medieval French fortified castle, destroyed in the 16th century. The first building was erected in the 13th century, adapted and altered into the 15th century.
The historic importance of the castle was due to its position on the frontier between Champagne (a vassal county of the King of France) and the Burgundy (a duchy allied with the English) during the Hundred Years War. At the time, the château de Bar-sur-Seine was considered the most important in Burgundy. Its architecture is close in style to that of the Château de Peyrepertuse in Aude.
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.