The construction of Don Álvaro de Luna castle was commissioned by the High Constable Ruy López Dávalos between the end of the 14th century and the beginning of the 15th century.There is very little left in the interior of the castle. The fires originating from the different wars have left, over time, only the walls of the building. In other periods it was used as a prison and cemetery, and today it is the municipal auditorium.
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.