The Mont Blanc Tunnel is a highway tunnel between France and Italy, under the Mont Blanc mountain in the Alps.It links Chamonix, Haute-Savoie, France with Courmayeur, Aosta Valley, Italy, via the French Route Nationale 205 and the Italian Traforo T1 (forming the European route E25), in particular the motorways serving Geneva (A40 of France) and Turin (A5 of Italy).