The first documentary reference to Santa María de Piasca is a donation from 930 making reference to a basilica just founded on the site. Little over a decade later, in 941, an agreement was recorded between 36 nuns and an unknown number of monks under an abbess Aylo, telling us that the monastery housed a community of both sexes. The monastery's dual character faced several oscillations, with the nuns leaving and returning twice. The archeological evidence of the original monastic buildings shows a small single nave church and separate spaces for the two groups.
A foundation stone records that the current church on the site, the Romanesque edifice, was dedicated in 1172 under a prior Petrus Albus. By this point the monastery had been incorporated into the larger Cluniac monastery of San Facundo y Primitivo de Sahagún (in 1122) and brought under the Benedictine Rule. The inscription also names the master of the project as Covaterio. The church has two sculpted portals, the west and the south. The portals have most likely been somewhat reconstructed, possibly with elements exchanged between the two. The triple arcade on the west façade has obviously been renovated as the central sculpture of Mary is from the sixteenth century. The two apostles (Peter and Paul) to her sides may have originally flanked an image of Christ, forming, as Ruth Bartal suggests, an abbreviated apostolado.
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.