northeast towards Suffolk. The Ridgeway meets the more recent (1997) Thames Path National Trail at the Goring Gap, where the trails use opposite banks of the River Thames between Goring-on-Thames and Mongewell; the Thames Path follows the western bank and the Ridgeway the eastern. The total height climbed along the path is . The official guide to the trail divides The Ridgeway into six sections. It is possible to join or leave the trail at other locations with public transport links including Avebury, Swindon, Wantage, Wallingford, Princes Risborough and Tring. The Ridgeway is one of four long-distance footpaths that combine to run from Lyme Regis to Hunstanton, collectively referred to as the Greater Ridgeway or Greater Icknield Way. The Ridgeway passes near many Neolithic, Iron Age and Bronze Age sites including Avebury Stone Circle; Barbury Castle, Liddington Castle, Uffington Castle, Segsbury Castle, Pulpit Hill and Ivinghoe Beacon Hill, all Iron Age and Bronze Age hill forts; Wayland's Smithy, a Neolithic chieftain burial tomb; the Uffington White Horse, an ancient chalk horse carved into the hillside near Uffington Castle; and Grim's Ditch, a section of earthwork near Mongewell created by Iron Age peoples as a possible demarcation line. Other points of interest include the Blowing Stone and Victory Drive, the private drive of Chequers (the British Prime Minister's country retreat). The Ridgeway's surface varies from chalk-rutted farm paths and green lanes (which have a propensity for becoming extremely muddy and pot-holed after rain) to small sections of metalled roads. Designated as a bridleway (shared with horses and bicycles) for much of its length, the Ridgeway also includes parts designated as byway which permits the use of motorised vehicles. Local restrictions along many byway sections limit the use of motorised vehicles to the summer months. Under the Countryside and Rights of Way Act 2000, many public rights of way in England and Wales that authorities had not explicitly classified as Bridleway or Byway defaulted to the classification "Restricted Byway" which precludes the use of motor vehicles at all times, except authorised vehicles and where required for access. As a result, much of the Ridgeway remains prohibited to motor vehicle use by the general public year-round. However, the Ridgeway is the only means of access for many farms, especially in the more remote parts of the Downs. Despite the Ridgeway's artificial creation, the TV programme Seven Natural Wonders featured it in 2005 as