This important historic site is in the hamlet of Salses, 15km (9 miles) north of the city center. Since the days of the Romans, this fort has guarded the main road linking Spain and France. Ferdinand of Aragón erected a fort here in 1497 to protect the northern frontier of his kingdom. This Spanish-style fort, designed by Ferdinand himself, is a curious example of an Iberian structure in France. In the 17th century, it was modified by the French military engineer Vauban to look more like a château. After many changes of ownership, Salses fell to the forces of Louis XIII in September 1642, and its Spanish garrison left forever. Less than 2 decades later, Roussillon was incorporated into France.