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.