Built in 333 BC along Gela's western coastline at Capo Soprano by the tyrant of Syracuse, Timoleon, Gela's ancient Greek fortifications are remarkably well preserved, most likely the result of being covered by sand dunes for thousands of years before their discovery in 1948. The 8m-high walls were originally built to prevent huge amounts of sand being blown into the city by the blustery sea wind. Today authorities have planted trees to act as a buffer against the encroaching sand.
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.