If option Selected - You will also have the opportunity to board the charming red cog railway up to Montenvers, you’ll enjoy fabulous views of Mer de Glace. This magnificent glacier is 4 miles (7km) long and averages just under a mile wide. Surrounded by the impressive summits of Les Drus, Les Grandes Jorasses and Les Grands Charmoz, The Montenvers site is a natural living witness of climate change of our era. It offers several visits including the crystal gallery or the Glaciorium, a new space entirely dedicated to the glaciers from their birth, to present and to the future. Depending on the period, it is also possible to visit the ice caves carved into the Glacier.