When Abraham Darby completed his ambitious project in 1779 to build the first cast-iron bridge in the world, he left behind no clues as to how he had achieved his success. The bridge near Telford in the UK, was the first structure to use the new material, and although there are many images of the finished bridge, there was no evidence of how it was constructed.
At first glance, the new pedestrian bridge being built over the Gave de Pau river in the south of France is just another modest cable-stayed span like hundreds of others being built all around the world.
