In French, the island is also known as Île de l’hôpital and Île de la Conférence. The most important historical event that took place on the island was the signing of the Treaty of the Pyrenees after a series of 24 conferences between Luis de Haro and Cardinal Mazarin in 1659 following the end of the Thirty Years' War. A monolith was built in the centre of the island to commemorate this event. The island was the site of many royal meetings: No visitors are allowed on the island.