Britannia Tubular Bridge (part in Llanfairpwllgwyngyll Community)

The Britannia Tubular Bridge, located partly in Llanfairpwllgwyngyll Community, is a Grade II listed structure. The bridge features piers made of rock-faced Anglesey limestone, known as Penmaen marble, set on a plinth, along with Runcorn sandstone and brickwork. Each of the two central water piers stands 67.5 meters (221 feet 3 inches) high from the foundation on the sea bedrock. These piers are constructed with rock-faced coursed stone and have battered sides, topped with an ashlar cornice raised on large corner blocks that create voids for suspension chains over rockers, all designed in an Egyptian Pylon style. The piers are voided, and stone lintels measuring 6 meters (20 feet) long span the rectangular openings for the twin tubes, with bold plat bands at the top and bottom of the tubes. Each side face features a symbolic engineering motif based on linked driving rods. The outer spans connect to similar abutment towers, which are flanked by sculptured lions on high plinths. A large figure of Britannia, designed by Thompson for the center pier, was never completed. The approach face is inscribed with 'Erected Anno Domini MDCCCL Robert Stevenson Engineer'.

The bridge was modified and reopened on June 11, 1980. It now consists of braced rivetted steel section arches with 'N'-truss spandrels spanning between the original piers, and the roadway is supported on stanchions above the railway. The side spans are constructed of reinforced concrete.