Mont-Louis (French pronunciation: [mɔ̃ lwi] ⓘ; Catalan: Montlluís or el Vilar d'Ovansa) is a commune in the Pyrénées-Orientales department in southern France.

[3] Mont-Louis is located in the canton of Les Pyrénées catalanes and in the arrondissement of Prades.

In 2008, the citadel and the city walls of Mont-Louis were listed as part of the Fortifications of Vauban UNESCO World Heritage Site, because of its outstanding engineering and testimony to the development of military architecture in the 17th through 19th centuries.

The citadel has been hosting for more than half a century the National Commando Training Center (French Army) which trains elite French troops and some foreign ones[example needed] in the usage of commando techniques and for enduring heavy physical and mental stress in combat situations.

Nevertheless, some places of the citadel, like the "Puits de Forçats",[7] can also be visited, being accompanied by a local guide.