Constantina Castle was dates back to the Moorish period, when it defended the north-south road towards Seville. It was conquered by Christians in 1274 and by the privilege of King Alfonso X in 1253, it passed to the Alfoz of Seville. In 1810, it was used as a fortified point during the period of the French invasion of the town.
Today the castle of Constantina consists of a polygonal enclosure of about ninety metres in diameter, which has an external defence in the form of a barbican, of which there are sufficient remains to affirm that it completely surrounded the enclosure. Most of this area has been preserved, and two of the seven towers that flanked it are still complete, containing magnificently built circular vaulted chambers.
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.