Salginatobel Bridge, Switzerland. This bridge was designed by the Swiss engineer Robert Maillart. Completed in 1930, it is a pioneering example of a three-hinged, hollow box arch bridge. It is made from reinforced concrete. At 132.30 metres long, it is Maillart's longest bridge. The bridge is over 90 metres high, carrying a single-lane road across the valley. Photographed near Schiers, Canton Graubunden.