�The Britannia Tubular Bridge�, Wales, c 1855.

UNITED KINGDOM - JUNE 04: Coloured lithograph drawn and lithographed by G Hawkins. The Britannia Tubular Bridge was designed by Robert Stephenson (1803-1859) and was completed in 1850. It was constructed to provide trains of the Chester and Holyhead Railway with a passageway across the Menai Straits from mainland Wales to Anglesey. The railway terminated at Holyhead, which became a major port for travellers to Ireland. Stephenson�s solution to the problem of how to carry the weight of trains pulling multiple carriages across the straits was to construct the bridge from rectangular iron tubes, through which the trains would run. (Photo by SSPL/Getty Images)