Peru's Nazca Lines are so big they weren't noticed until airplanes existed

Between roughly 200 BC and 500 AD, the Nazca people scraped away desert rock to trace hundreds of giant figures and lines across the plains of southern Peru, some running for miles. Most went largely unremarked on the ground and only drew wide attention once commercial pilots spotted them from the air in the 1930s. Archaeologists still debate whether they marked astronomy or honored water gods.

— Anthony F. Aveni, Between the Lines: The Mystery of the Giant Ground Drawings of Ancient Nasca, Peru — University of Texas Press, 2000
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