The Tanfield Railway was originally built to transport coal from the collieries of County Durham, to the staithes on the River Tyne.
The route and structures of the oldest section of the now preserved part of the line, between Sunniside and Causey, dates from 1725, and is thus claimed to be the World's oldest working railway
Originally a wooden railed horse drawn wagonway, conversion to a conventional steel railed railway began in 1837, and by 1840 was complete as far as Tanfield Moor Colliery.
The Marley Hill sheds contain a large amount of mine related material.