Naut Aran is a municipality in the comarca of the Val d'Aran in Catalonia, Spain. It is the second largest municipality in Catalonia in terms of surface area, and was created in 1967 by the merger of the municipalities of Arties, Salardú, Gessa, Tredòs and Bagergue: the former municipalities retain some privileges as "decentralised municipal entities". The name literally means "Upper Valley" in Aranese, and both the Garonne and the Noguera Pallaresa have their sources on the territory of the municipality. The town hall is in Salardú. The municipality is linked to Vielha by the C-28 road, which continues to Alt Àneu over the Port de la Bonaigua. This road, the higher stretches of which are impassable in winter, was the only route between the Aran Valley and the rest of Spain before the opening of the Vielha tunnel in 1948.
The local economy is based almost entirely on tourism and winter sports. The ski resort of Vaquèira-Beret is one of the largest in the Pyrenees. A number of local churches have been classified as historic-artistic monuments:
church of Sant Andreu de Salardú, which houses a thirteenth-century sculpture of Christ
church of Santa Maria, in Arties