The Aragonese Castello di Brucoli was built in the 15th century as a watch tower to guard the coast and monitor and protect against Turkish-Barbarian raids. It underwent several additions and alterations in the following centuries, e.g walls with circular towers at the corners were added in the 16th century.
The Castle of Brucoli dominates much of the Gulf of Catania and was therefore used as a watch and guard post in the 18th century, hosting a military garrison in the employ of the nearby fortress of Augusta. It guarded also the port of Brucoli.
Despite the effects of time, the castle is in good condition.
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.