The Britannia Tubular Bridge was constructed by Robert Stephenson to carry two lines of railway in rectangular wrought-iron tubes across the Menai Strait; it was opened in 1850. There were four spans between masonry piers and carved stone lions stood sentinel at each end. In 1970 a fire severely damaged the tubes and the bridge was rebuilt in 1972 as an arched steel structure, using the original masonry towers, carrying a single line of railway. In 1980 an upper deck was completed, carrying the two-lane A55 North Wales Expressway (nprn 403728).
B.A.Malaws, RCAHMW, 01 November 1999.

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The Britannia Bridge was constructed by the civil engineer Robert Stephenson as a tubular railway bridge over the Menai Strait. The commissioning of the Britannia Bridge followed the opening of Thomas Telford's Menai Suspension Bridge, which had revolutionised coach travel between Holyhead and London. With the steadily increasing number of travellers between Ireland and Wales however, the construction of a railway line across the strait became necessary. Work on the bridge started in 1846 and four years later it was opened to the public.

To complete a bridge of this span, supporting the weight of two railway tracks was a difficult prospect. Following the same conditions that had been put in place when Telford designed the Menai Suspension Bridge, Stephenson's railway bridge also had to be high enough to allow ships to sail below it at all times. Stephenson came up with a revolutionary new tubular design that allowed a greater span without the need for suspension trains, testing this design with his construction of the smaller railway bridge across the estuary at Conwy, opened in 1849. The masonry of the Britannia Bridge uses ancient Egyptian designs and four enormous lions, also in Egyptian style, decorate the entrances to the bridge on both sides.

Like the Menai Suspension Bridge, countless tourists flocked to the Britannia Bridge throughout its construction and after it was opened. For a long period, visitors were even allowed to explore the inside of the tubes! One excited account by the German traveller Rudolph Delbruck relates how, during a particularly hot and dry summer, the wooden roof of the tubes had dried out and caught fire from the sparks of the passing train. In turn, the burning tubes set the luggage ablaze which was carried on top of the train.

Following a substantial fire in 1970, the tubular girders were removed as they were deemed to have become structurally instable due to the heat of the blaze. The bridge was reconstructed and now features two decks, the lower one still allowing trains to cross the Menai Strait, while the top carries the A55 road. The original masonry piers support the new structure and the stone lions are still in place.

Record updated as part of the AHRC-funded project 'Journey to the Past: Wales in historic travel writing from France and Germany'.
R. Singer (Bangor University) and S. Fielding (RCAHMW), 2017.