Ancient Aviators (aka Ancient Flight)

In this episode we investigate the mysterious markings on the plains of Nazca in Peru. What are these mysterious markings, who made them, and why? Were they an ancient landing field for aliens? The signs and symbols of various birds and insects are only discernible from the air. How then could the ancient Nazca's have made them unless they had an aerial view in which to work them out? What are the mysterious arrow straight lines that seem to lead nowhere and why are they there? These and other strange markings in the area make us wonder who made them and why? Were they man made or did someone else put them there?