The Tren a las Nubes is a tourist train service in Salta Province, Argentina. The service runs along the eastern part of the Salta–Antofagasta railway line of the Belgrano Railway that connects the Argentine Northwest with the border in the Andes mountain range, over 4,220 metres (13,850 ft) above mean sea level, the fifth highest railway in the world. Originally built for economic and social reasons, it is now primarily of interest to tourists as a heritage railway, though cheaper tickets are also available for locals to use the train as transport.

Salta is a province of Argentina, located in the northwest of the country. Neighboring provinces are from the east clockwise Formosa, Chaco, Santiago del Estero, Tucumán and Catamarca. It also surrounds Jujuy. To the north it borders Bolivia and Paraguay and to the west lies Chile.