The Château du Girsberg is one of three castles (with the Château de Saint-Ulrich and the Haut-Ribeaupierre) which overlook the municipality of Ribeauvillé.
The Lords of Ribeaupierre built the castle, then named Stein (La Roche), in the 13th century. They rebuilt it after a fire caused by lightning in 1288. In 1304, they gave it to their vassals, the knights of Guirsberg, from whom the castle took its name. The Guirsbergs kept it until they died out in the 15th century. It was abandoned in the 17th century.
The remains currently visible contains 13th century pentagonal keep, inner court and corps de logis from the 14th-15th centuries.
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.