The Millau bridge over the River Tarn in the Massif Central mountains is more than 300m (984ft) high - taller even than the country's Eiffel Tower.

The bridge, which opens to traffic on Thursday, was built to clear summer traffic jams around the town.

The BBC's Paris correspondent, Caroline Wyatt, says the bridge is one of the most breathtaking ever built.

She says that with its concrete and steel pillars soaring high above the morning fog in the Tarn Valley, the construction makes a spectacular sight.

'Delicacy of a butterfly'

Seven slender piers support the roadway, rising into seven graceful pylons bound to the bridge with what look like cobwebs of steel, our correspondent says.

"The bridge is just on the clouds," Millau Mayor Jacques Godfrain told the BBC's World Today programme.

"The architect, Norman Foster, gave us a model of art."

TALL ORDER Cost: 394m euros (£272m; $524m) Highest point: 343m (1,125ft) Vehicle height: 270m (885ft)   In pictures: The Millau bridge

"A work of man must fuse with nature. The pillars had to look almost organic, like they had grown from the earth," the world-renowned British architect said in an interview with regional daily newspaper Midi Libre.

Like Concorde and the Channel Tunnel, the bridge is Franco-British.

French construction group Eiffage - that built the Eiffel Tower - financed the project in return for the right to collect receipts from a bridge toll for 75 years.

The bridge is now a source of pride for Millau, which believes many more tourists will come to admire one of the engineering wonders of the 21st Century, our correspondent says.

The construction also removes a bottleneck at the town, completing a new motorway link between Paris and the Mediterranean.

The construction of the steel bridge - now weighing about 36,000 tonnes - began in December 2001, using innovative techniques.

From the north and south sides of the valley, the metal sections of the structure were assembled, lifted slightly and then carefully slotted into place on each of the supporting pillars.