The Tamar Valley is an area of outstanding natural beauty in Devon and Cornwall, consisting of the Tamar, Lynher and Tavy valleys, as well as surrounding areas. To the east, the region is bordered by the Dartmoor National Park, and to the south lies the city of Plymouth. The Tamar Valley was the site of much mining activity during the 18th and 19th centuries, including the construction of Devon Great Consols, believed to be the worlds largest copper mine. The Tamar Valley includes part of the Cornwall and West Devon Mining Landscape World Heritage Site.