Fort San Lucian is a large bastioned watchtower and polygonal fort in Marsaxlokk, Malta. The original tower was built by the Order of Saint John between 1610 and 1611, being the second of six Wignacourt towers. An artillery battery was added in around 1715, and the complex was upgraded into a fort in the 1790s. In the 1870s, the fort was rebuilt by the British in the polygonal style.
Saint Lucian Tower is the second largest watchtower in Malta, after Saint Thomas Tower. Today, the tower and fort are used by the Malta Aquaculture Research Centre.
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.