One of the most compelling arguments for the Ancient Astronaut theory is the remarkable engineering evident in the construction of ancient megalithic sites worldwide. Even with the most advanced machinery available today, replicating these ancient wonders would be a daunting task. The colossal stones, precise cuts, and perfectly fitted blocks at many of these sites hint at the fascinating prospect of advanced technology. Join experts Giorgio Tsoukalos, William Henry, and Jason Martell as they embark on a global investigation, revisiting the series archives of "Ancient Aliens" to explore the most enigmatic archaeological sites, including Giza, Puma Punku, Nan Madol, Baalbek, and others.