Viaduc de Garabit in Val d'Arcomie

You're standing by the Garabit viaduct, a railway bridge high above the Truyère river, in the mountains of France's Massif Central. Start with that big red arch. It leaps across the valley in a single span of a hundred and sixty-five metres. The whole viaduct is about five hundred and sixty-five metres long, and the track runs more than a hundred and twenty metres above the water.