Holsterburg was built by brothers Hermann and Bernhard Berkule before 1191. It was destroyed in local war in 1294. After its destruction, the Holsterburg was covered with a mound of earth, probably also for symbolic reasons, to erase the Berkule family and their ancestral seat from the memory of posterity. Under the hill, the complex has been preserved as it was in 1294.
The hill was excavated in 2010-2017 and castle ruins were cleaned.
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.