This is listed by Wikipedia as the tallest concrete gravity dam in the world, 285m high, and at an altitude of 2,365 metres. It is also the highest level accessible for tourists on an architectural structure in Europe, after the restaurant of Tower in Moscow. However, there is currently a taller dam at Nurek in Tajikistan which is 300 metres.
Visitors can take a guided tour inside the dam to explore some of the maintenance tunnels, and also take a cable car to the top where this photograph was taken.
The dam holds back a lake, the Lac des Dix, which is usually full of water by late September, and empties during the winter, reaching its lowest point around April. This photograph was taken in June 2008, when the water level was still low, as can be seen from the lighter coloured 'tide mark' on the surrounding rocks.