"Ancient Astronauts" is a theory suggesting that extraterrestrial beings visited Earth in ancient times and influenced human civilization. Proponents believe these visitors shared advanced knowledge and technology, which helped shape early cultures, architecture, and religions. Supporters often point to ancient structures like the Pyramids of Giza and Stonehenge as evidence of advanced engineering that they argue could not have been achieved by humans alone. They also reference ancient texts and myths from various cultures that describe gods or beings descending from the sky, interpreting these as potential accounts of alien encounters.