Chivert Castle (or Xivert Castle) is located along the south-western foothills of the Sierra de Irta. It is of Muslim origin, dating from the late 11th to early 12th centuries, but following the reconquest of the square by Christian forces under the command of the Knights Templar, it underwent subsequent modifications that can still be seen today. For example, the separation of the castle and the town by means of a wall, the imposing stonemasonry walls and twin circular towers.
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.