Derwent Valley Mills is a World Heritage Site along the River Derwent in Derbyshire, England, designated in December 2001. It is administered by the Derwent Valley Mills Partnership. The modern factory, or 'mill', system was born here in the 18th century to accommodate the new technology for spinning cotton developed by Richard Arkwright. With advancements in technology, it became possible to produce cotton continuously. The system was adopted throughout the valley, and later spread so that by 1788 there were over 200 Arkwright-type mills in Britain. Arkwright's inventions and system of organising labour was exported to Europe and the United States.
Water-power was first introduced to England by John Lombe at his silk mill in Derby in 1719, but it was Richard Arkwright who applied water-power to the process of producing cotton in the 1770s. His patent of a water frame allowed cotton to be spun continuously, meaning it could be produced by unskilled workers. Cromford Mill was the site of Arkwright's first mill, with nearby Cromford village significantly expanded for his then-new workforce; this system of production and workers' housing was copied throughout the valley.