Tren a las Nubes, which means "Train to the Clouds" in English, is a famous train journey in Argentina that travels through the Andes mountains, offering stunning views of the landscape. The train journey starts in the city of Salta in northwestern Argentina and takes passengers through a number of small towns and villages, over bridges and through tunnels, and up to an elevation of 4,220 meters (13,845 feet) above sea level.

The train journey takes around 16 hours, including stops, and covers a distance of around 434 kilometers (270 miles). The train passes through various landscapes, including mountains, canyons, and the high plateau of the Puna region, and offers passengers the chance to see local wildlife, including llamas, condors, and vicuñas.

The train journey was first inaugurated in 1972 and was originally used to transport goods and supplies to remote villages in the Andes mountains. In the 1990s, it was converted into a tourist attraction, and today it is one of the most popular tourist experiences in Argentina. The train operates during the high season from April to November, and it is recommended to book tickets in advance due to its popularity.