The Château du Grand-Geroldseck is a ruined medieval castle situated in Haegen, Alsace. The castle is one of the oldest in the northern Vosges, founded at the beginning of the 12th century by the lords of Geroldseck, avoués of the abbey of Marmoutier, to ensure the protection of its territories. It constitutes a fine collection of feudal residence. Built on a platform, it combined the functions of dwelling and defence. It was heavily altered at the 13th, 14th and 15th centuries.
The square keep has walls three metres thick, faced in embossed stone. The cellars of the lord's residence and the barbican are still visible.
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.