A short walk, but full of interest and the steep gradient makes it feel longer than it is. Not only is the Lumsdale Valley is one of the best surviving water-powered industrial sites in England, it is also home to a number of picturesque waterfalls and mill ponds that would be worth visiting even if you have no interest in Industrial Archaeology.
The Bentley Brook, which flows down the valley, once provided the power for a series of mills manufacturing a range of different products: gunpowder, cotton spinning, bleaching, grinding corn, bone and minerals for paint manufacture.
Historian Martyn Gillie of the Arkwright Society organises guided tours in the summer. There is a leaflet giving full details of the walk available at their Cromford Mill shop, or contact him direct (see comments below).