La Chartreuse de la Verne, Carthusian monastery in Collobrieres, was built in 1174, however in 1264 and 1271 it was burned down. It wasn't until the sixteenth century that the present chapel and the great south gate were built.
The current Chartreuse is a lovely and imposing set of buildings, completely isolated in a hilly forest of pine, oak and chestnut, overlooking the artificial lake, Lac de la Verne.
The drive up to the monastery is a beautiful scenic trip. A community of nuns still lives in the building, making ceramics and other crafts for sale at their shop.
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.