The Ridgeway is a ridgeway or ancient trackway described as Britain's oldest road. The section clearly identified as an ancient trackway extends from Wiltshire along the chalk ridge of the Berkshire Downs to the River Thames at the Goring Gap, part of the Icknield Way which ran, not always on the ridge, from Salisbury Plain to East Anglia. The route was adapted and extended as a National Trail, created in 1972. The Ridgeway National Trail follows the ancient Ridgeway from Overton Hill, near Avebury, to Streatley, then follows footpaths and parts of the ancient Icknield Way through the Chiltern Hills to Ivinghoe Beacon in Buckinghamshire. The National Trail is 87 miles (140 km) long.