Mont-Louis (Catalan: Montlluís or el Vilar d'Ovansa) is a commune in the Pyrénées-Orientales department in southern France.
In 2008, the citadel and the city walls of Mont-Louis were listed as a UNESCO World Heritage Sites, as part of the "Fortifications of Vauban" group.
The Mont-Louis Solar Furnace, is the world's first solar furnace, built in 1949, by engineer Felix Trombe. It is open to visit for practical education on solar energy uses and technologies.