Testa Grigia (Aosta Valley)Testa Grigia is a mountain on the Italian side of the Monte Rosa Massif in the Pennine Alps. It is the highest mountain of the ridge that separates the Lys valley from the Ayas Valley, in Aosta Valley.AscentIt is usually climbed from the Gressoney side, where the climb presents no technical difficulties, as the route is assisted by a fixed rope. The summit offers a fine balcony view of Monte Rosa and the Matterhorn.