Church of Santa María a Real do Sar was built in the 12th century on the outskirts of the city. Interesting elements on the exterior are the small tower on the façade and the sturdy flying buttresses built between the 17th and 18th centuries. It has a basilical floor plan with three naves, separated by composite pillars decorated with plant motifs. It is covered with barrel vaults reinforced by rib arches. The sanctuary of the collegiate church has three apses; the central one is polygonal and the two side ones are semicircular. The interior lighting comes from the side openings and the rose window on the façade. Elements worth noting in the cloister include the decoration on the capitals, made by the workshop of Master Mateo.
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.