The Monastery of San Pedro de Villanueva is a Romanesque monastery previously owned by the order of Benedictines. A church here supposedly was founded by Alfonso I the Catholic, son in law of Pelagius of Asturias. The remaining structures now date from later periods. In the 12th century, the monastery was built adjacent to the church. The buildings underwent substantial rebuilding after the 17th century. In 1835, the monastery was dissolved. In the present century, the monastery has become a national hotel, a Parador. The church is still in use.
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.