Maidenhead Railway Bridge, also known as Maidenhead Viaduct and The Sounding Arch, carries the Great Western Main Line (GWML) over the River Thames between Maidenhead, Berkshire and Taplow, Buckinghamshire, England. It is a single structure of two tall wide red brick arches buttressed by two over-land smaller arches. It crosses the river on the Maidenhead-Bray Reach which is between Boulter's Lock and Bray Lock and is near-centrally rooted in the downstream end of a very small island.

The Great Western Main Line (GWML) is a main line railway in England that runs westwards from London Paddington to Bristol Temple Meads. It connects to other main lines such as those from Reading to Penzance and Swindon to Swansea. The GWML is presently a part of the national rail system managed by Network Rail while the majority of passenger services upon it are provided by the current Great Western Railway franchise.