Conwy railway bridge carries the North Wales coast railway line across the River Conwy between Llandudno Junction and the town of Conwy. The wrought iron tubular bridge was built by Robert Stephenson to a design by William Fairbairn, and is similar in construction to Stephenson's other famous tubular bridge, the Britannia Bridge across the Menai Strait. Each tube weighed 1,300 tonnes and was floated into position on pontoons. It was then raised by hydraulic presses. At each end of the bridge are fine castellated towers which harmonise with the adjacent castle ruins.

The bridge was officially opened in 1849, but had been completed in 1848. Being the first tubular bridge to be built, the design needed much testing on prototypes to confirm that it would be capable of carrying heavy locomotives, the testing being performed by Fairbairn with loads of up to 300 tons of iron. The successful result enabled the much larger Britannia bridge to be built. The current bridge has been reinforced by extra columns under the bridge into the river, but is otherwise virtually unchanged since it was built.

The Conwy railway bridge runs parallel to an elegant suspension bridge built by Thomas Telford (see entry), which is now in the care of the National Trust, and is open to pedestrians only. These crossings of the Conwy resemble in miniature the two greater crossings of the Menai Strait.

Since the destruction by fire of Britannia Bridge in 1970, Conwy railway bridge remains the only surviving example of this means of construction undertaken by Stephenson. It is a scheduled Ancient Monument.