This is not a museum with a ticket desk: it sits high up, on the penstock track of the Gran Balconata del Cervino, near the La Mande pastures and the dam of Lake Goillet, and is partly housed in a building of the Valdostan water company.
What to see
The panels explain how the waters of the Marmore were put to work generating electricity, and what is left of the worksites of the Vertice, the Tracciolino, the Les Perrères power station and the reservoir, all built between the 1920s and the 1930s. Outside stand the machines themselves: the cable winch that hauled the trolley from the Les Perrères plant up to the Vertice, an Agudio starting device, the Brown-Boveri motor unit and the trolleys that ran level along the Tracciolino as far as the foot of the dam. Higher up the slope is the building from which the tunnel to the dam sets out.
Visiting
You come from the Bec del Pio Merlo, dropping south to the Alpe Promindot and then following the dirt road. It is a walking destination, not a drive-up one: count it as a stage in a day spent at altitude.
Our editors' tip
Anyone walking here for the Matterhorn will spend the whole time looking up; it is worth stopping and looking down, where the mountain was wired. This is the part of Valdostan history that no castle tells.