For the halfway point in our bridge-themed A-Zdvent calendar, we've chosen the Millau Viaduct by Foster + Partners, a colossal bridge that spans a gorge in southern France.

Stretching 2.46 kilometres across the Tarn Valley, the cable-stayed structure was built to relieve traffic in the picturesque town of Millau.

Each of its sections spans 342 metres, and its masts range in height from 75 metres to 245 metres. When completed in 2004 it took the title of world's tallest bridge and even superseded the Eiffel Tower as the tallest structure in France.

Foster + Partners won a competition to design the structure in 1993, partnering with engineer Eiffage. Unlike other entrants, who suggested bridges at the base of the valley, the team felt the best solution was to connect the two high plateaux at either side.

Seven equally spaced concrete piers support the road deck. Each one tapers towards the top but splits into two as it meets the road to create a needle-like eye that flexes to accommodate any expansion and contraction of the deck.

"The elegance of its design means it enhances rather than damages the natural landscape," said Dezeen editor-in-chief Marcus Fairs in his book 21st Century Design.

Founded by British architect Norman Foster, the UK architecture studio has completed a vast number of projects around the world, but only a small number of bridges.

They include the Årsta rail and pedestrian bridge in Stockholm, completed in 2005, and the Millennium Bridge in London, which opened in 2000.

The latter, a pedestrian bridge that crosses the River Thames between Tate Modern and the City of London, was closed almost immediately due to swaying, reopening in 2002.

In the spirit of an advent calendar, Dezeen is counting down the days until Christmas with an A to Z of iconic contemporary bridges. See all the bridges in our A-Zdvent calendar so far »

Photography is by Ben Jonson unless stated otherwise.