Andělská Hora, originally called Engelsburg, is a castle above the village of Andělská Hora, about 7 kilometres southeast of Karlovy Vary. The ruins of the castle stands upon a rock overlooking the village of Andělská Hora which lies just below. It was founded at the turn of the 14th to the 15th century by Boreš z Rýznburk, a noblemen from the Rýznburk family, as protection for their estates. The castle was destroyed by fire during the Thirty Years' War and abandoned in the 17th century.
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.