Montorio Castle was presumably a look-out post which was once part of the Verona city fortifications and which is first mentioned in documents dating back to 995 AD. It was subsequently rebuilt by the Aldobrandeschi in the Middle Ages and restructured by the Ottieri and then transformed into a fortified farmhouse after the annexation of the county in the Grand Duchy of Tuscany. Only certain sections of the structure remain, as four of the seven towers were demolished (as well as parts of the walls) by the Austrians in 1820. The castle now serves as a venue for cultural events held in the summer.
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.