The Ducal Palace of Béjar was built after 1203 by Alfonso VIII. Although these already very reduced in the XIXth century, they still conserve some square and round towers and part of their perimeter bordering the oblong hill on which the old part is based. Béjar was a royal place, but with Enrique III, in 1396, it passed to the lordship of Diego López de Zúñiga or Estúñiga, whose successors will hold the title of dukes of that place, granted by the Catholic Monarchs.
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.