The Millau Viaduct crosses the Tarn valley in southern France, standing tall enough that its highest pylon reaches 343 metres, taller than any other bridge on earth. The film follows the engineering behind a structure built to solve a real problem: a major highway used to run straight through the town of Millau, choking it with traffic on the route from Paris to the Mediterranean. Structural engineer Michel Virlogeux and architect Norman Foster explain their design in interviews, along with Millau's mayor Jacques Godfrain, covering why the bridge curves with a 20-kilometre radius and slopes 3% for driver visibility. The construction sequence gets particular attention: seven concrete pylons went up first, then the 36,000-tonne steel roadway was pushed out across them in stages using hydraulic rams moving it 600 millimetres at a time, with masts added only after the deck was fully in place. Footage from the top of a pylon shows the French countryside from a height almost nobody gets to see. The result is 2,460 metres of roadway that also became the world's longest cable-stayed deck.