Carcassonne Cathedral was built in the 13th century as a parish church, dedicated to Saint Michael. Following war damage in the 14th century it was rebuilt as a fortified church. In 1803 St. Michael's was elevated to cathedral status, replacing the earlier cathedral dedicated to Saints Nazarius and Celsus, now the Basilica of St. Nazaire and St. Celse.
The cathedral plan is characterised by its relative simplicity. It forms a single nave with a 20 metre high vault, lined with several lateral chapels. The chior screen has retained its 14th century stained glass. The sober façade has a single decorative feature in the form of a large rosette 8 meters in diameter, and the adjoining bell tower is relatively massive.
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.