Throughout history it's been said that many of humanity's greatest achievements came from the stars. Renowned alien expert Giorgio A. Tsoukalos takes us through some of the most remarkable. 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.