The River Dove is a famous trout stream, 45 miles in length. Charles Cotton's Fishing House, the inspiration for Izaak Walton's "The Compleat Angler", stands in the woods by the river. From Hartington to its confluence with the River Manifold at Ilam the River Dove flows through the scenic limestone valley known as Dove Valley, or Dovedale. From Hartington south to Ilam, a distance of eight miles (13 km), the Dove flows through Beresford Dale, Wolfscote Dale, Milldale, and then Dovedale. Much of the dale is in the ownership of the National Trust's South Peak Estate. Dovedale was acquired in 1934, with successive properties added until 1938, and Wolfscote Dale in 1948. Dovedale became a National Nature Reserve in 2006 in recognition that it is "one of England's finest wildlife sites" with diverse plant life and interesting rock formations. The National Trust became embroiled in controversy in 2010, when in conjunction with Derbyshire County Council it oversaw the renovation of Dovedale's iconic stepping stones. It involved topping all but one of the stones with layers of mortar and limestone slabs. At the southern end of Dovedale, at between the villages of Thorpe and Ilam, stands Thorpe Cloud, , an isolated limestone hill known as a reef knoll. It provides a viewpoint north up the dale and south across the Midlands plain. Its name "cloud" is a derivation of the Old English word "clud" which means "hill". On the opposite bank, at , is the higher but less isolated Bunster Hill, , which is also a reef knoll. They were acquired by the National Trust in 1934 for the South Peak Estate. Milldale is a village of stone cottages at the northern end of Dovedale and the main access point to the dale from the north. A corn mill existed until the mid-19th century, its stables are now used as an information hut by the National Trust. The ancient, narrow packhorse bridge at Milldale originally had no side walls so that horses with panniers could cross the bridge without being impeded. Izaak Walton, who refers to himself as "Viator", which is Latin for "traveller", wrote about it in "The Compleat Angler":  From this the bridge acquired the name Viator's Bridge. The bridge has been in use since the medieval period, for packhorses transporting silks and flax from nearby Wetton and Alstonefield.