The
Susa Valley (, , ) is a valley in the
Piedmont region of northern
Italy, located between the
Graian Alps in the north and the
Cottian Alps in the south. It is the longest valley in Italy. It extends over in an east-west direction from the
French border to the outskirts of
Turin. The valley takes its name from the city of
Susa which lies in the valley. The
Dora Riparia river, a tributary of the
Po, flows through the valley.