San Giovanni Castle, located on a high rock spur near Bondone, has a breathtaking panorama. It was first mentioned in 1086 and formally in 1189. In the 15th century the castle was occupied by Milanese troops. The abandoned and decayed castle was bought by entrepreneur Milan Luigi Cavalli in 1956 who began a renovation to turn it into a private residence. Today it can be visited.
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.