The Citadel aka Fort de Charlemont is an amazing venue. Nowadays it is exploited by event organizer "Agimont Adventures" and was untill recently, used by the French Defense Forces for training their commando's. This Citadel has several large fields for playing paintball in which the most famous in this realm, is "The Village.." You will have a hard time finding a better place for playing CQB games, even in the rest of forts and Barracks riddled Europe.