Aosta is the principal city of the Aosta Valley, a bilingual region in the Italian Alps, 110 km (68 mi) north-northwest of Turin. It is situated near the Italian entrance of the Mont Blanc Tunnel, at the confluence of the Buthier and the Dora Baltea, and at the junction of the Great and Little St Bernard Pass routes.

The Aosta Valley is a mountainous autonomous region in northwestern Italy. It is bordered by Auvergne-Rhône-Alpes, France, to the west, Valais, Switzerland, to the north, and by Piedmont, Italy, to the south and east. The regional capital is Aosta.