Starigrad Fortress was built during the Croatian–Ottoman wars (15th century) as a primary defence against the Ottoman Empire. The precipitous fortification is sited on a 262 m ridge above the town Omiš. In the event of attack, its purpose was to provide refuge for local people and be a stronghold where they could retreat to and resist the Turks.
As the stone fort's defensive strength is derived from the elevation at which it was built, it is a rudimentary defensive structure. A two-storey square tower stands at its highest point, serving as both a lookout post and keep. A simple bastion stands at the opposite end of the fort to cover the approach path and the ridge line. It has an outer barbican to defend the fort's narrow entrance gateway and the gorge below the fort. The walls, which are about 1 m thick, are made from locally quarried limestone. They enclose an inner bailey that is separated into two distinct levels by the difference in the site's natural rock height. Access between the levels is via a small stone stairway that was once protected by a stone wall and gateway. In event of attack, the fortification's design permits the defenders to fall back to higher ground as each level falls.
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.