Castle of Alba de Aliste is located on the margins of the river Aliste. Today it lies in ruins. In the 12th century it belonged to the Knights Templar. Don Álvaro de Luna owned it in the 15th century. It became the capital of the county of Alba y Aliste under Enrique IV.
It was built on the remains of an old Vetton fort in the 12th century and renovated in the 15th century, retaining only some walls and a tower, although it had an irregular plan of 30 meters wide and 70 long, four towers, barbican and crenellated.
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.