Conwy bridges over the Conwy River, Wales. The suspension bridge (down centre) was designed by Thomas Telford and opened in 1826. It is a chain as opposed to a cable design, and now used as a pedestrian bridge that leads to Conwy Castle (bottom centre). The tubular rail bridge (upper right) is built into the castle's battlements, and was designed by Robert Stephenson and opened in 1848. It was the world's first box girder bridge. It is made of wrought iron and one end rests on rollers to allow the structure to expand and contract. The road bridge (down left) was opened in 1958.