Neuhaus castle dates probably back to the 13th century. It may have been built on the site of earlier 12th century fortified house. The pentagonal tower was added in the 14th century and the castle was rebuilt during the 16th century. The traffic on the Danube has been able to deny with chain from the chain tower, located below the castle. Neuhaus was besieged at least in 1381, 1386 and 1389.
References:I visited, and vacationed at Neuhaus in 1960. I have oil paintings of the castle and a floral watercolor that was given to my parents from the baroness who owned it and lived there.
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.