History's Greatest Mysteries: Season 4, Episode 19

4 - 19: Unlocking the Secrets of the Nazca Lines

They've been called the world's greatest archaeological enigma. 2,000-year-old geoglyphs made in the Peruvian desert that span over 50 miles. The drawings are so massive, they can only be seen from the air. Can new research finally unravel their secrets? What is the true purpose of the incredible Nazca Lines?