The importance of Coria in Roman times is reflected in its defensive military fortification erected during the Early Roman Empire (1st century). Its layout is the shape of an irregular trapezoid featuring solid walls of granite ashlar masonry, completed with the traditional pattern of stretcher and header bond on their faces and the internal reinforcement with a 3-metres-thick layer of concrete. These walls are defended by twenty-three robust square or cube-shaped towers, each located about 20 or 30 metres apart, surrounding its total perimeter of 1,065 metres. The imposing fortification extends across six hectares of land, as the walls adapt to the uneven terrain with their width occasionally exceeding 4 metres and their height ranging between 10 and 14 metres.
These enormous defensive walls protect its boundaries and give access through four entrance gates: to the north, the Puerta de San Pedro/Puerta del Sol (1st century); to the southwest, the Puerta de la Guía/Puerta de la Ciudad (1st century); to the northwest, the Puerta de San Francisco/Puerta del Rollo (16th century); and to the east, the Puerta del Carmen/Puerta Nueva (16th century). These huge gates are reminiscent of the Roman domination and presence in the territory. Although, throughout its extensive history, this borderland has been subjected to alterations and several episodes of war, the Roman City Walls of Coria, as a whole, are arguably among Europe’s best-preserved fortifications.
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.