Le Perthus became French territory after the Treaty of the Pyrenees (1659). The Spanish captured Bellegarde in 1674 and began work on new fortifications in 1675. These were not very far advanced when the place was recaptured by the French. In 1678 Vauban designed for Bellegarde a strong pentagonal fort with a detached hornwork extending southwards towards the frontier.
The defences consist of a five bastioned trace, with an upper tier and a lower tier. In front of the more vulnerable sections of wall, there is a ditch. There are three demi-lunes, again only on the more approachable sides of the fortress - on the east there is a sheer precipice.
During the War of the Pyrenees, the fortress was besieged in May - June 1793 by the Spanish and then by the French (in 1794).
During World War II, the fort was used as a holding prison by the Gestapo for escaped prisoners of war and enemy agents.
The fort is open to the public between June and September only and includes exhibits on the history of the fort, its archaeology and the surrounding area.
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.