Tarn (river) a mean flow of approximately . The Millau Viaduct spans the valley of the Tarn near Millau, and is now one of the area's most popular attractions. The tributaries of the Tarn include: The Tarn separates the Narbonne and Aquitaine basins. The Tarn passes through the following departments and towns: The Millau Viaduct, the tallest bridge in the world, carrying the A75 autoroute across the Tarn Gorge near Millau, opened in December 2004. The Tarn is famous for its brutal floodings, which are the most dangerous in Europe along with the Danube. The flooding of March 1930 saw the Tarn
Millau of the Tarn and Dourbie about 340 m altitude. The territory surrounding the town of Millau is characterized by livestock production and the maintaining of natural grasslands, fields and temporary pastures. It also consists of a multitude of gorges, ravines and defiles which are the defining characteristic of this country. These predominantly agricultural rural areas like the rest of this fragile region, are protected by the Regional Natural Park of Grands Causses. The flora in the area has more than 2000 species. There is a variety of asparagus with triple leaves, Montpellier aphyllanthe, honeysuckle from the Etruria region of Italy.