Montenvers Railway, Chamonix
This train has been chugging up to the Mer de Glace for over 100 years; a ride up to the longest glacier in France is a must. Winding its way up the side of the mountain, amongst the pine forests and through dark tunnels of rock it emerges beside the Mer de Glace at 1913m. As well as the glacier itself you can also visit a crystal museum, ice caves, the Temple of Nature, the Glaciorium and the historic Grand Hotel du Montenvers.
If you are accompanied by a mountain guide you can even go onto the glacier to see the crevasses and bottomless holes close up!
The Montenvers train is included in the Mont Blanc Unlimited lift pass, along with the Aiguille du Midi cable, the Tramway du Mont Blanc and various other activities.