Cologne Charterhouse (Kölner Kartause) was a Carthusian monastery established in 1334. The monastery developed into the largest charterhouse in Germany until it was forcibly dissolved in 1794 by the invading French Revolutionary troops. The building complex was then neglected until World War II, when it was mostly destroyed. The present building complex is very largely a post-war reconstruction. Since 1928 the Carthusian church, dedicated to Saint Barbara, has belonged to the Protestant congregation of Cologne.
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.