site to promote sustainable tourism and travel. Location and coverage The Derwent Valley Mills World Heritage Site covers an area of and spans a stretch of the Derwent Valley, in Derbyshire, from Matlock Bath in the north to Derby city centre in the south. Within the site are mill complexes, settlements including workers' housing, weirs on the River Derwent, and the transport network that supported the mills in the valley. The site consists of the communities of Cromford, Belper, Milford, and Darley Abbey, and includes 838 listed buildings, made up of 16 Grade I, 42 Grade II*, and 780 Grade II. A further nine structures are Scheduled Ancient Monuments. The buildings are a mixture of mills, workers' housing, and structures associated with the mill communities. The Cromford Canal and Cromford and High Peak Railway, which aided the industrialisation of the area, are also part of the World Heritage Site. History In the late 17th century silk making expanded due to demand for silk as part of fashionable garments. In an attempt to increase production through the use of water power, Thomas Cotchett commissioned engineer George Sorocold to build a mill near the centre of Derby on an island in the River Derwent. Although the experiment was unsuccessful, it convinced John Lombe – an employee of Cotchett – that if water power could be perfected there was a market for its produce. He engaged in industrial espionage and gained plans of Italian machines. He patented the design in 1719 and built a five-storey mill next to Crotchett's mill. By 1763, 30 years after Lombe's patent had expired, only seven Lombe mills had been built because the silk market was small, but Lombe had introduced a viable form of water powered machinery and had established a template for organised labour that later industrialists would follow. As silk was a luxury good, the market was small and easily saturated by machine produced goods. The next innovation in machine produced textiles came in the cotton industry which had a much wider market and produced more affordable goods. Spinning cotton was a more complex process than silk production. The water frame for spinning cotton was developed by Richard Arkwright and patented in 1769. The machines could spin yarn continuously and replaced skilled workers with unskilled supervisors to make sure the machines did not break. Water frames varied in size from 4 to 96 spindles. For