The French autoroute that carries the Millau Viaduct is the A75.
Known as la Méridienne, the A75 runs south from Clermont-Ferrand toward Béziers and forms part of the major A75–A71 axis linking the Paris region with southern France. The Millau Viaduct crosses the Tarn valley near Millau in Aveyron and completes the A75’s route through that dramatic landscape.
The cable-stayed viaduct was designed by engineer Michel Virlogeux and architect Norman Foster. Construction began in 2001; it was inaugurated on 14 December 2004 and opened to traffic two days later. Its deck is about 2,460 metres long, supported by seven piers and seven masts.
The phrase “tallest bridge in the world” needs qualification. Millau was long described as the tallest by structural height, reaching 343 metres, but newer Chinese bridges have taken world records for deck height or overall structural height. The highway answer remains A75.