Col du mont Cenis, France

Mont Cenis is a massif and pass (2,081m) in Savoie, France, which forms the limit between the Cottian and Graian Alps, and the road over the pass was built between 1803 and 1810 by Napoleon. A 'Fell' mountain railway system, named after its inventor John Fell and worked by English engine-drivers, was opened alongside the road in 1868, but was dismantled in 1871, on the opening of the Mont Cenis Tunnel. The tunnel is 13 km in length, and leads to Bardonecchia, some way below which, at Oulx the line joins the road from the Col de Montgenèvre. It was the principal route for crossing the Alps between France and Italy until the 19th century. It was also used as the main passage by which Charlemagne crossed with his army to invade Lombardy in 773.