Built outside the walls to the north of the walled enclosure, San Martín Church has a Roman origin, as confirmed by the latest archaeological explorations. After the Roman building had been apparently ruined, it was rebuilt and radically transformed in the 16th century and at the beginning of the 18th century.
In the 14th century, the tower was built on a base made of granite ashlar work and an upper body made of brick. It also stands as a belfry of Gothic tradition and shows evidence of the Mudejar Masters. The pointed openings are of particular interest and are made of decreasing horseshoe archivolts set in a panel.
In the 16th century, the layout was completed and structured into three naves separated by semi-circular arches. In the 18th century, the Main Chapel was refurbished and the side chapel and semi-spherical cupola above the Presbytery were built. Two Roman altar stones were reused in the south wall.
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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.