Castell y Bere is a Welsh castle near Llanfihangel-y-pennant in Gwynedd, Wales. Constructed by Llywelyn the Great in the 1220s, the stone castle was intended to maintain his authority over the local people and to defend the south-west part of the princedom of Gwynedd. In 1282, war with Edward I of England resulted in the death of Llywelyn's grandson, Llywelyn ap Gruffudd, and Castell y Bere fell to English forces.
Edward I expanded the castle further and established a small town beside it. In 1294 the Welsh leader Madog ap Llywelyn mounted a major revolt and the castle was besieged and apparently burnt. Edward did not repair it and it became ruined. Today it is in the hands of Cadw and operated as a tourist attraction.
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.