Colmar is a city and commune in the Haut-Rhin department and Alsace region of north-eastern France. The third-largest commune in Alsace, it is the seat of the prefecture of the Haut-Rhin department and of the subprefecture of the Colmar-Ribeauvillé arrondissement. The city is renowned for its well-preserved old town, its numerous architectural landmarks and its museums, among which is the Unterlinden Museum, which houses the Isenheim Altarpiece.