The Millau Viaduct (French: le Viaduc de Millau, Occitan: lo Viaducte de Milhau) is an enormous cable-stayed road-bridge that spans the valley of the river Tarn near Millau in southernFrance. Designed by the structural engineer Michel Virlogeux and British architect Norman Foster, it is the tallest vehicular bridge in the world, with one mast's summit at 343 metres (1,125 ft) ? slightly taller than the Eiffel Tower and only 37 m (121 ft) shorter than the Empire State Building.

The viaduct is part of the A75-A71 autoroute axis from Paris to Montpellier. Construction cost was around ?400 million. It was formally dedicated on 14 December 2004, inaugurated the day after and opened to traffic two days later. The bridge won the 2006 IABSE Outstanding Structure Award. The Millau Viaduct is located on the territory of the communes of Millau and Creissels, France, in the drtement of Aveyron. Before the bridge was constructed, traffic had to descend into the Tarn River valley and pass along the route nationale N9 near the town of Millau, causing heavy congestion at the beginning and end of the July and August vacation season. The bridge now traverses the Tarn valley above its lowest point, linking two limestone plateaus, the Causse du Larzac and the Causse Rouge, and is inside the perimeter of the Grands Causses regional natural park.
The bridge forms the last link of the A75 autoroute, (la Mdienne) from Clermont-Ferrand to Pnas (to be extended to B'ers by 2010). The A75, with the A10 and A71, provides a continuous high-speed route south from Paris through Clermont-Ferrand to the Languedoc region and through to Spain, considerably reducing the cost of vehicle traffic travelling along this route. Many tourists heading to southern France andSpain follow this route because it is direct and without tolls for the 340 kilometres (210 mi) between Clermont-Ferrand and Pnas, except for the bridge itself.
The Eiffage group, which constructed the viaduct, also operates it, under a government contract which allows the company to collect tolls for up to 75 years. The toll bridge costs ?5.60 for light automobiles (?7.40 during the peak months of July and August).
The Millau Viaduct consists of an eight-span steel roadway supported by seven concrete pylons. The roadway weighs 36,000 tonnes and is 2,460 m (8,070 ft) long, measuring 32 m (105 ft) wide by 4.2 m (14 ft) deep, making it the world's longest cable-stayed deck. The six central spans each measure 342 m (1,122 ft) with the two outer spans measuring 204 m (669 ft). The roadway has a slope of 3% descending fromsouth to north, and curves in a plane section with a 20 km (12 mi) radius to give drivers better visibility. The pylons range in height from 77 m (253 ft) to 246 m (807 ft), and taper in their longitudinal section from 24.5 m (80 ft) at the base to 11 m (36 ft) at the deck. Each pylon is composed of 16 framework sections, each weighing 2,230 tons. These sections were assembled on site from pieces of 60 tons, 4 m (13 ft) wide and 17 m (56 ft) long, made in factories in Lauterbourg and Fos-sur-Mer by Eiffage. The pylons each support 87 m (285 ft) tall masts.
The enormous pylons were built first, together with intermediate temporary pylons which were in themselves a massive record-breaking construction project.
Remarkably, the entire length of deck surface (that is to say, the bridge itself, the actual kilometers of roadway) was slid out, into the valley, across the pylons from both sides.
This feat was achieved using hydraulic rams that moved the deck about 600 mm every 4 minutes, over the course of many days.
While the kilometers of roadway was being slid-out through space, it was supported by both the final pylons and the temporary pylons.
Only after the roadway was completely slid-out in to the final position, were the masts erected on top of the deck (that is to say, over the pylons). To be clear, the masts on top are not continuing elements of the pylons underneath, although they appear to be. The masts are separate constructions which were built on land, wheeled out to position only after the pylons and roadway were complete, raised (with difficulty), and emplaced.

The construction of the massive cable-stay system between the masts and deck then followed. Finally, the massive temporary pylons in the valley were removed.
Construction began on 10 October 2001 and was intended to take three years, but weather conditions put work on the bridge behind schedule. A revised schedule aimed for the bridge to be opened in January 2005. The viaduct was inaugurated by President Chirac on 14 December 2004 to open for traffic on 16 December, several weeks ahead of the revised schedule.
The construction of the bridge was depicted in an episode of the National Geographic Channel MegaStructures series, as well as Discovery Channel's Extreme Engineering, both of which included time-lapse footage of the ultimate astonishing feat of sliding the roadway out over the valley, on to the plyons, to create the bridge.