The Mezquita was built from a visigothic basilica from the 5th century, reusing its materials, and is one of the few surviving Spanish rural mosques.
It is an oddly-shaped building, made of brick and stone in a trapezoid shape, probably because of the hilly terrain. The oration room has 5 naves, whose arches, like in the Mezquita in Cordoba, are perpendicular to Qibla. The central nave is wider than the 2 nearby, which are in turn wider than the 2 outer naves. The Mihrab has lost its paint, and looks quite archaic; only the brick and stone is visible. In the oration room, 16 undated tombs were found.
When Spain became Christian, many changes were made, including the addition of a central axis in accordance with the new religion. The old door and the North flank were also reconstructed. Despite these changes, the whole building still retains a rustic charm.
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.