Cubbie Roo's Castle, built about 1150, is one of the oldest castles in Scotland and was mentioned in the Orkneyinga Saga. It takes its name from Kolbein Hruga who was said to have lived there. In King Haakon's saga, it is mentioned that after the last Norse Earl of Orkney, Earl John, was murdered in Thurso, his killers fled to Wyre. They took refuge in the castle, which was so strong that the besiegers had to thrash out a deal with them to get them out.
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.