San Sebastián is a fortress located in Cádiz, at the end of La Caleta beach on a small island separated from the main city.
According to the classical tradition of the location of the fortress, there was a Temple of Kronos, a Titan of the Greek gods, the father of Zeus, Poseidon, Hades, Hestia, Demeter and Hera. In 1457, a chapel on the island was raised by a Venetian boat crew recovering from the plague. In 1706, a castle was constructed, which resulted in a fortified enclosure of an irregular plane. It defended the northern flank of the city from attack. At the base of the lighthouse was a watchtower from the Muslim period. The lighthouse has an iron structure designed by Rafael de la Cerda in 1908 and is the second electric powered lighthouse in Spain. The tower rises to 41 meters above the sea.
In 1811 the Maltese navy arrived with the famous POW/rebel Junta of Buenos Aires, Juan Bautista Azopardo. He was housed in the fortress until 1815, when they suspected a leak and transferred him to the military prison in Ceuta.
In 1860, a levee was built to serve as a link between the island and the city. On June 25 of 1985, Castillo de San Sebastian was declared a cultural landmark.
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.