In the north, Aosta valley is separated from the Swiss Valais (the valley of the Rhône) by the Valais Alps. The Great St Bernard Pass leads over this mountain range to Martigny. Other passes over the Valais Alps are only accessible on foot. The Valais Alps here form a traffic-impermeable barrier between the Aosta valley and Valais. In the northwest, Aosta Valley is bordered by the Mont Blanc massif. To the south and east, the Aosta Valley borders the Italian region of Piemonte.