Chûn Castle is a large Iron Age hillfort (ringfort) near Penzance in Cornwall. The fort was built about 2,500 years ago, and fell into disuse until the early centuries AD when it was possibly re-occupied to protect the nearby tin mines. It stands beside a prehistoric trackway that was formerly known as the Old St Ives Road and the Tinners’ Way.
The fort was excavated in 1895, 1925, 1927 and 1930. Much pottery was uncovered; the earliest was dated to the 4th century BC due to its similarity to known Breton pottery of that age. But the fort may have been built upon a much older structure. Chûn Quoit, around 800 feet to the west, is dated to around 2400 BC. It is believed that the fort fell into disuse around the first century AD but was reoccupied and modified several centuries later, until the 6th century. However, occupation may also date to the later Roman period.
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.