Giorgio Tsoukalos and David Childress explore the mysterious chain of manmade islets in Micronesia's Nan Madol, built from 250 million tons of volcanic rock, Might the site's powerful magnetic anomalies be the result of extraterrestrial technology? Ancient Aliens examines 75 million years of the most credible alien evidence here on Earth: from the age of the dinosaurs, to ancient Egypt, to the skies over the western desert in the present day US, ancient cave drawings of strange creatures, an asphalt-like substance in an Egyptian pyramid made from the remains of unidentified creatures, continued mass sightings in the USA.