The Tower of Motta Sant'Anastasia was built between 1070 and 1074 by the will of the Count Roger of Hauteville. The massive tower with a rectangular plan, with a base of about 21.5 by 9 by 17 metres, is about 21 metres high and is a typical defensive structure of the early Middle Ages. The roof terrace retains almost intact battlements.
The structure consists of three elevations. Only the first of these is still the original arched windows ogive (external) and at all sixth (inside). The other two square windows, on other levels, such as the current front door, go back to the 15th century.
The ground floor was designed for military housing. In it there are a number of holes for defence.
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.