Aberystwyth Castle was built in response to the First Welsh War in the late 13th century, replacing an earlier Motte and bailey castle located a mile to the south. The current castle was rebuilt in its current location by Edward I of England in 1277 after the end of the first war against Llywelyn ap Gruffydd Llywelyn the Great's grandson. The Welsh took the castle in 1282 at the start of the 1282 war and burned both the castle and the town. Under master mason James of St George, the castle was eventually completed in 1289, though it was sieged extensively during the revolt of Madog ap Llywelyn in 1294–5.
During a national uprising by Owain Glyndŵr, the Welsh captured the castle in 1404, but it was recaptured by the English four years later. In 1637 it became a Royal mint by Charles I, and produced silver shillings. The castle was slighted by Oliver Cromwell in 1649.
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.