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
Rio–Antirrio bridge and a pedestrian walkway. Its five-span four-pylon cable-stayed portion of length is the world's third longest cable-stayed deck; only the decks of the Jiaxing-Shaoxing Sea Bridge in Shaoxing, China and the Millau Viaduct in southern France are longer at 2,680 m (8,793 ft) and , respectively. However, as the latter is also supported by bearings at the pylons apart from cable stays, the Rio–Antirrio Bridge deck might be considered the longest cable-stayed "suspended" deck. This bridge is widely considered to be an engineering masterpiece, owing to several solutions applied to span the difficult site. These difficulties include deep water, insecure