The Castle of Arnóia is a medieval castle in civil parish of Arnóia, municipality of Celorico de Basto, the district of Braga. It was built in the late 11th or early 12th century, probably to defend the local monastery. The abandonment occurred from 1717, when elites left the small village of Basto, moving the seat of the county to the parish of Britelo, where today is located Celorico de Basto.
Today there are four defensive elements survived: the watchtower (whose rooftop and set of battlements were reconstructed in the 20th century), the quadrangular tower, a single door and the tank.
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.