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, in particular the motorways serving Geneva and Turin. The passageway is one of the major trans-Alpine transport routes, particularly for Italy, which relies on this tunnel for transporting as much as one-third of its freight to northern Europe. It reduces the route from France to Turin by 50 kilometres and to Milan by 100 km. Northeast of Mont Blanc's summit, the tunnel is about 15 km southwest of the tripoint with Switzerland, near Mont Dolent.
The agreement between France and Italy on building a tunnel was signed in 1949. Two operating companies were founded, each responsible for one half of the tunnel: the French Autoroutes et tunnel du Mont-Blanc, founded on 30 April 1958, and the Italian Società italiana per azioni per il Traforo del Monte Bianco, founded on 1 September 1957. Drilling began in 1959 and was completed in 1962; the tunnel was opened to traffic on 19 July 1965.