The Monastery of Santa María de Mezonzo is a Romanesque style former monastery. Although it probably dates back to the time of the Kingdom of the Suebi, the current monastery was founded as a double convent by Abbot Reterico. According to Antonio López Ferreiro, the monastery was donated to the Asturian-Galician king Alfonso III el Magno in 870. Justo Pérez de Urbel, after comparing the names of the confirmatory of several documents related to the monastery, thinks that the correct date is the one given by Hinojosa, that is, the year 930.
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.