Two valleys climb up towards the Monte Rosa massif, the Ayas Valley and the Gressoney Valley. The former arrives at the foot of the amphitheatre of mountain peaks that runs from the Breithorn to the Castore, starting out from Verrès and passing through the municipalities of Challand-Saint-Victor, Challand-Saint-Anselme, Brusson and Ayas; while the latter peaks at the mountainside that runs from the Castore to Punta Gnifetti, where the "Regina Margherita" mountain hut and science laboratory was built in 1893.

On the way up the Gressoney or Lys Valleys you will pass through Perloz, Lillianes, Fontainemore, Issime, Gaby, Gressoney-Saint-Jean and Gressoney-La-Trinité.

Both the valleys, especially in the upper part, were affected by the migration that in the 12th - 13th centuries led the Walser peoples to move from the Valais to various other areas south of the Alps. For several centuries, the two valleys were communication and trade routes linking the Aosta Valley, Valais and Piedmont, until the advance of the glaciers that began in the 14th century made the high mountain passes impracticable.