The Mont Blanc massif; ; ) is a mountain range in the Alps, located mostly in France (Haute-Savoie and Savoie) and Italy (Aosta Valley), but also straddling Switzerland (western Valais) at its north-easterly end. It is named after Mont Blanc which, at 4,810 m, is regarded as the highest point in western Europe. Not only does the massif form a watershed between the vast catchment areas of the Rhône and Po rivers, but it also marks a border between two climate regions by separating the northern/western Alps from the southern Alps.