The Mont Blanc Tunnel is a highway tunnel in Europe, under the Mont Blanc mountain in the Alps. It links  Chamonix, Haute-Savoie, France with Courmayeur, Aosta Valley, Italy, via European route E25. The passageway is one of the major trans-Alpine transport routes, particularly for Italy, which relies on the tunnel for transporting as much as one-third of its freight to northern Europe. It reduces the route from France to Turin by and to Milan by . Northeast of Mont Blanc's summit, the tunnel is about southwest of the tripoint with Switzerland, near Mont Dolent.