Built between 1967 and 1972, the dam blends perfectly with the surrounding rocky landscape. The best way to arrive is by funicular (the world's steepest), which commands a splendid view of the Mont Blanc range. The 180m-high curved dam holds back 225 million m3 of water. In a geological paradox, the water here originates from the Mont Blanc range on the other side of the valley, arriving through underground galleries before rising thanks to a natural siphon phenomenon.