The Paddington/Bristol Railway is represented by the Bristol Temple Meads terminus including the Great Western boardroom, the Box Tunnel west portal, the Swindon railway works and village, the Maidenhead river bridge and the Paddington station terminus and hotel as well as by the general engineering of the route and its gradients. This is regarded as the most complete early railway in the world.
The line was built in the 1840s in accordance with Stephenson's concept of a level line achieved by driving deep cuttings and tunnels. Brunel's Great Western Railway is regarded among other important early UK railways, including the London and Birmingham, the Liverpool and Manchester and the Stockton and Darlington as best representing the primary phase of world railway development. The Great Western is the best preserved of this group.