In the 13th century, the San Juan del Hospital Church was the priory of the Knights of the Order of St. John of Jerusalem with a hospital attached and it was converted into a military parish in the 18th century. Built around 1261, it is considered to be the first church built after the Christian conquest. Its combination of the synthesis and elegance of Romanesque tradition with the new gothic architecture and the fact that it has the only cemetery dating from medieval times in Valencia, led to its classification as a National Historic and Artistic Monument in 1942.
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.