Alessandria Cathedral is dedicated to Saints Peter and Mark. It is the seat of the Bishop of Alessandria. A diocese centred on Alessandria was created in 1175 by Pope Alexander III, and a cathedral dedicated to Saint Peter was built as the bishop's seat at that time. It was too small however, so was demolished and rebuilt between 1288 and 1297. This cathedral was demolished for military tactical reasons on the order of Napoleon Bonaparte in 1803.
The dispossessed bishop and chapter received the permission of the French general of the occupying troops to elevate the church of St Mark to the status of cathedral. This church had been built in the 13th century for the use of the Dominicans. The French troops had commandeered it in 1797 for quarters. The church had however to be rebuilt: this took place from 1807 to 1810, and the new Neo-classical cathedral, named after both Saint Peter and Saint Mark, opened in December 1810.
A major restoration was carried out from 1875 to 1879, and the cathedral was actually consecrated only in 1879, at the end of these further works. The interior was badly damaged by fire in 1925, and was extensively refurbished between 1925 and 1929.
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.