Puertas de Tierra is a bastion-monument built around remnants of the old defensive wall at the entrance to the city of Cadiz. Built by academic architect Torcuato Cayón in the 18th century, the cover is carved in marble and was intended more as a religious altarpiece than as a military fortification.
It is one of the most significant monuments of the city and on its walls flies the purple flag of its canton.
The adjustment to the new architecture of the city, opening the two new arcs, is performed by the architect Antonio Sánchez Esteve.
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.