The name has Roman origins and it indicates the distance of nine miles between Aosta and Nus. Saint-Barthelemy is the best known hamlet thanks to the astronomical observations.

Nus covers an overall area of 57 km². The name has Roman origins: it derives from ad nonum (ab Augusta) lapidem, that is nine miles between Aosta and Nus. There are traces of settlements of the Bronze and Iron Ages; moreover, some brickworks and other objects, such as coins and medals, have been found among the ruins of the so called “Pilatos’s” Castle.

The area is characterized by grasses, chestnut woods and vineyards. The “Vien de Nus” is one of the products of the area. Saint-Barthelemy is the best known hamlet thanks to the well-known astronomical observatory, the seat of the most ancient Italian Star Party. During the summer mountaineers and hikers go to Saint-Barthelemy Valley, whereas during the winter this place is chosen by keens on cross-country skiing and on downhill skiing.