The ruins located within the walls of Peel Castle are those of the former Cathedral of St German. Like the structures throughout the castle grounds, the cathedral's roof is completely missing. Robert Anderson examined the ruins to determine what repairs were required to restore the cathedral, and he reported to the island's Lieutenant Governor in 1877. However, none of the suggested repairs were carried out.
There is a pointed barrel-vaulted crypt below the chancel, measuring 10 × 5 × 3 metres, sloping to the entrance at the east. There is a cemetery in what was once the cathedral's nave.
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.