The Train to the Clouds is one of Argentina's most famous railway journeys — a 434-kilometre round trip from Salta that climbs to 4,220 metres above sea level before crossing the La Polvorilla viaduct, a dramatic steel arch bridge over a desert gorge. The journey takes around 15 hours in total and involves a remarkable series of zigzags and switchbacks as the narrow-gauge line ascends from the Lerma Valley into the high puna.
Departures are infrequent (typically Saturdays during the April–November season) and tickets should be booked well in advance. Altitude sickness (soroche) is a genuine concern on this trip — the train spends several hours above 3,500 metres. Coca leaves and medication are available on board. The journey is slow, the scenery is extraordinary, and the viaduct at the end justifies the whole day. For those who want a shorter version, there are tourist excursion options to intermediate stops.