Guise castle is a medieval fortification in the town of Guise, in northern France. Originally an early medieval wooden motte and bailey castle, it was rebuilt in stone and then massively expanded during the 12th-16th centuries. It was remodelled by Marquis de Vauban in the late 17th century to meet the advances in sIege technology then taking place. Much of the castle was reduced to rubble during the First World War and, from 1952 onwards, it has been undergoing restoration by the Club du Vieux Manoir. Nowadays it is a popular tourist site.
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.