San Andrés church was built in the quarter of Ajates (a suburb of mediaeval origin in which the main trade was masonry) in the second quarter of the 12th century. It was made in Caleno granite (very typical of the Romanesque style in the town) and is set according to liturgical criteria with an upper end with three apses that correspond to the three naves in the interior; it does not have a transept nave. The protruding central apse is of particular interest thanks to the number of figures and capitals and the closed arches on the straight section of the upper end, which stand as a unique example of Romanesque capitals. The variety of icons on the interior and exterior capitals is the largest of all of Ávila's Romanesque buildings and is associated with the Masters of León. The central apse has two absidioles of a smaller size and a plainer composition.
The upper end is covered with decreasing stepped vaults: barrel vaults along the straight section and calotte vaults along the curved section. The southern absidiole has a lobulated arch used as the entrance and unparalleled in any other church in Ávila at the time.
The south front has a semi-circular window and the keystone of the semi-circular archivolt contains a Chi Rho which, fitted in the 13th century, is considered as the first of its kind in the town. The tower stands next to the western side, built onto the nave during or after the 14th century.
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.