Chariots of the Gods?, written by Erich von Däniken, was first published in 1968. It became an international bestseller. The thesis of the book is that ancient human civilizations had contact with visitors from outer space. These "ancient astronauts" were supposedly responsible for many of the great architectural feats of history, such as the Egyptian pyramids, the Nazca lines of Peru, and the statues on Easter Island.

Mainstream archaeologists dismiss von Däniken's argument as pseudoscience. A charitable view of von Däniken would credit him with really believing all the arguments he makes. A more cynical view paints him as a knowing hoaxer. For instance, one of his central arguments is that it would have been impossible for past civilizations to build monuments such as the pyramids. But von Daniken refuses to consider contradictory evidence. In fact, many theories adequately explain how these monuments could have been built by early civilizations with the technology of the time.

Von Däniken also invents facts. In a follow-up book, The Gold of the Gods, he described visiting the "Caves of Gold" located beneath the jungles of Ecuador, where the treasure of the Incas is supposedly hidden. Here he saw a vast library of metal books containing the writings of the ancient astronauts. However, von Däniken was not willing to disclose the location of these Caves of Gold. There is no evidence they exist outside of his imagination.