Conwy Castle was built by Edward I, during his conquest of Wales, between 1283 and 1287. Constructed as part of a wider project to create the walled town of Conwy, the combined defences cost around £15,000, a massive sum for the period. Over the next few centuries, the castle played an important part in several wars. It withstood the siege of Madog ap Llywelyn in the winter of 1294–95, acted as a temporary haven for Richard II in 1399 and was held for several months by forces loyal to Owain Glyndŵr in 1401.
Following the outbreak of the English Civil War in 1642, the castle was held by forces loyal to Charles I, holding out until 1646 when it surrendered to the Parliamentary armies. In the aftermath, the castle was partially slighted by Parliament to prevent it being used in any further revolt, and was finally completely ruined in 1665 when its remaining iron and lead was stripped and sold off. Conwy Castle became an attractive destination for painters in the late 18th and early 19th centuries. Visitor numbers grew and initial restoration work was carried out in the second half of the 19th century. In the 21st century, the ruined castle is managed by Cadw as a tourist attraction.
UNESCO considers Conwy to be one of 'the finest examples of late 13th century and early 14th century military architecture in Europe', and it is classed as a World Heritage Site. The rectangular castle is built from local and imported stone and occupies a coastal ridge, originally overlooking an important crossing point over the River Conwy. Divided into an Inner and an Outer Ward, it is defended by eight large towers and two barbicans, with a postern gate leading down to the river, allowing the castle to be resupplied from the sea. It retains the earliest surviving stone machicolations in Britain. In keeping with other Edwardian castles in North Wales, the architecture of Conwy has close links to that found in the Kingdom of Savoy during the same period, an influence probably derived from the Savoy origins of the main architect, James of Saint George.
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.