The shapes drawn out by the famous Nazca lines in the Peruvian desert are at their most evident from the air—giving rise to some famously fantastic theories about their origin. The new understanding offered here is the result of a piece of straightforward brilliance on the part of our authors: get down on the ground, where the original users were, and see where your feet lead you. Using stratigraphic and taphonomic reasoning to decide which lines were contemporary, they discover an itinerary so complex they can justify calling it a labyrinth, and see it as serving ceremonial progressions.