Section of cellular base of main span N tube from Britannia bridge. 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 & Holyhead Railway with a pasageway acros the Menai Straits from mainland Wales to Anglesey. The railway terminated at Holyhead, which became a major port for travellers to Ireland.
© Science Museum / Science & Society Picture Library