View of the La Polvorilla viaduct in Salta Province, Argentina. The Train a las Nubes (or Train to the Clouds) runs through the viaduct and connects the Argentine Northwest with the Chilean border in the Andes mountain range 13,850 ft above mean sea level. (Flickr/Alicia Nijdam)


Traveling by rail can be the most relaxing, most scenic journeys you could take. But with steep climbs on almost-vertical hills, zig-zagging tracks on cliff faces, or narrow bridges over cyclone-prone, high-wind locations, some train rides can get your heart pounding a little bit faster and harder. Here, we explore the most memorable railways routes in the world, which offer passengers both hair-raising thrills and breathtaking views.

Argentina's Tren a las Nubes (or "Train to the Clouds") is one of the highest railways in the world, taking passengers 13,850 feet up to the spectacular landscapes of the Andes Mountain Range. It leaves from the province of Salta, the lowest point on the line, to the La Povorilla Viaduct, the highest (and one of the most vertigo-inducing) points on the trip, according to its official website. Along the way, the train passes through 29 bridges, 21 tunnels, 13 viaducts, two spirals and two zigzags. The trip lasts approximately 16 hours.