Minchinhampton and Rodborough Commons are two linked sweeps of open limestone grassland on the Cotswold escarpment above the Stroud valleys and the Severn Vale. The Trust rates Minchinhampton Common an important archaeological landscape, with prehistoric field systems, burial mounds and the defensive earthwork known as The Bulwarks. Rodborough Common, just to the north, came to the Trust in 1937 from the lepidopterist Thomas Bainbrigge Fletcher and is known for pasque flowers, early purple orchids and more than 30 species of butterfly, among them the Duke of Burgundy and the Adonis blue, which returned after an absence of 40 years. Rodborough Fort was built as a folly in 1761 for Captain George Hawker. Four circular Trust trails of 1 to 2.75 miles start on Rodborough Common, including the Rodborough Fort walk and the butterfly walk. Dogs must be under close control, and on a short lead around livestock and in spring and summer for ground-nesting birds. Cattle and horses graze freely, so the Trust asks drivers to take care and never park on the grass; the ground is uneven and can be boggy after rain.