The Tanfield Railway is a 4 ft 8+1⁄2 in standard gauge heritage railway in Gateshead and County Durham, England. Running on part of a former horse-drawn colliery wooden waggonway, later rope & horse, lastly rope & loco railway. It operates preserved industrial steam locomotives. The railway operates a passenger service every Sunday, plus other days, as well as occasional demonstration coal, goods and mixed trains. The line runs 3 miles (4.8 km) between a southern terminus at East Tanfield, Durham, to a northern terminus at Sunniside, Gateshead. Another station, Andrews House, is situated near the Marley Hill engine shed. A halt also serves the historic site of the Causey Arch. The railway claims it is "the world's oldest railway" because it runs on a section dating from 1725, other parts being in use since 1621.

Marley Hill is a former colliery village about six miles to the south west of Gateshead, near the border between Tyne and Wear and County Durham. It has been part of the Metropolitan Borough of Gateshead since 1974. Prior to this it was part of Whickham Urban District. It lies within the Whickham South & Sunniside electoral ward of the Blaydon parliamentary constituency.