Are they ancient road maps or messages for visiting aliens? Lying at the foothill of Perus Andes Mountains is the site of one of the worlds greatest mysteries. Etched, as if by giants, onto it's arid, moonscape plains are immense lines that stretch for miles to form strange shapes recognizable only from the air. Forming the shapes of animals, plants and humans, they were first spotted by pilots in the 1930s, and inspired fantastic explanations ever since. Now, a team of specialists from around the globe has come to southern Peru to investigate the Nasca Lines in the hope of uncovering their secrets.