Andrew Marr goes on a journey to discover how some of the greenest landscapes in the British Isles were in fact shaped and moulded by human hands down the centuries.He looks at the ancient 'wild wood' and Iron Age forts lurking in Britain's forests to the present-day strain modern economic needs put on the countryside, and how town planners restrict urban growth through the establishment of greenbelt areas.He also looks down on Britain's national parks to show how we go to extraordinary lengths to preserve them as beautiful but artificial playgrounds. We also see how Britain's rugged landscape is used as the ideal testing ground for the Eurofighter.