Located 4,000 meters above the sea level in the Andes, Tren a las Nubes or “Train to the clouds” is one of the highest railways in the world. It begins its journey from the city of Salta, in Argentina, at an altitude of 1,187 meters, passes through the Valle de Lerma, enters the Quebrada del Toro and finally ends its journey at the La Polvorilla viaduct (4,200 meters). During the 16-hour trip, the train travels 217 km and climbs a staggering 3,000 meters. It crosses 29 bridges, 12 viaducts, 21 tunnels, swoops round two gigantic loops and two switchbacks. Train to The Clouds got its name from the numerous clouds that are often seen under bridges and around slopes.

The route was laid down in the 1920s by American engineer Richard Fontaine Maury, who was in charge of the project. He designed a singular system supported by bridges, tunnels, viaducts, spirals and zigzags. The zigzags allow the train to climb the mountain by driving back and forth parallel to the slope of the mountain. Maury didn’t use funiculars or cogwheels that are normally used on steep slopes, instead relying on switchbacks to gain height.

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