The ruins of the ancient town of Castrotorafe, popularly known as Zamora la Vieja, are in San Cebrian de Castro, emplacement already located in the 12th century.
It was a medieval defensive site which appeared on the banks of Esla River. It keeps the walls built with slate masonry and mortar, and has 4.709 square meters, including the castle, the hermitage and the walls.
The best preserved is the castle, of two enclosures with irregular trapezoid shape. Inside of it, practically ruined, built with different materials and with a floor similar to the outside.
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.