An astonishing feat of engineering the Tren a las Nubes (Train to the Clouds) is a trajectory of over 220 km. It passes through the magnificent Quebrada del Toro gorge high up into the Andes mountain range before crossing the mecano-like Viaducto La Polvorilla to the little village of La Polvorilla at an altitude of some 4,200 metres (although at Abra Chorillos it goes as high as 4,475 metres). The train used to continue on to Chile via Chorillos to Socompa, crossing the third largest salt lake in the world.

The line was originally constructed in 1948 in order to facilitate the transport of borax but today it is exclusively dedicated to tourism. It crosses 29 bridges, passes through 21 tunnels, traverses 13 viaducts, follows two enormous loops and chugs along two switchbacks. Made in Italy, the carriages possess an elegant interior with leather upholstery and polished wood. On the journey, the train passes through the small villages of Campo Quijano and San Antonio de los Cobres, where it is greeted by locals selling their handicrafts. Here you can disembark while the train doubles back. The journey takes some 15 hours from Salta and back.

The Tren a las Nubes runs several times weekly during July and August. From April to October it runs several times a month, but usually only as far as Estacion Diego de Almagro, at some 3,500 metres, during which time it is dubbed the Tren del Sol (to the sun). Tickets should be purchased in advance, single or return from La Veloz del Norte Turismo on Caseros 400, tel: +54 (0) 387 431 1010 or Movitren on Caseros 431, tel: +54 (0) 431 4984. The trains leave from Estacion Belgrano on Ameghino 690, tel: +54 (0) 387 431 0999. Go to the website Tren a las Nubes for detailed information about schedules and prices. Alternatively, it’s possible to travel up by train and return by 4WD vehicle along the Track a las Nubes. Or you can do both ways by car if you prefer. Otherwise tour operator Movitrack runs the Safari a las Nubes in a truck which travels besides the line.