Cheddar Gorge is a limestone gorge and the site of the Cheddar show caves, where Britain's oldest complete human skeleton, Cheddar Man, estimated to be 9,000 years old, was found in 1903. Older remains from the Upper Late Palaeolithic era (12,000–13,000 years ago) have been found.The caves, produced by the activity of an underground river, contain stalactites and stalagmites. The gorge is part of a Site of Special Scientific Interest called Cheddar Complex. Cheddar Gorge, including the caves and other attractions, has become a tourist destination. In a 2005 poll of Radio Times readers, following its appearance on the 2005 television programme Seven Natural Wonders, Cheddar Gorge was named as the second greatest natural wonder in Britain, surpassed only by Dan yr Ogof caves. The gorge attracts about 500,000 visitors per year.