Löwenburg castle was built around 1200 by the Counts of Sayn. Together with the Castle of Blankenberg high above the valley of river Sieg it secured their territory. In the second half of the 13th century the old keep was torn down. Only then the castle whose ruins we see today was built. In the late Middle Ages the Löwenburg went through an eventful history until it fell to the Counts of Berg in 1484. It was destroyed in the Thirty Years War.
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.