The history of Hindsgavl Castle dates back to the 12th century, and the name Hindsgavl was mentioned for the first time in the Danish register of manors and estates by King Valdemar II in 1231. Valdemar IV of Denmark besieged the castle with no luck in 1358. The current castle was built in the late 18th century. Today Hindsgavl is a conference center.
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.