"Chariots of the Gods" is a book that attempts to prove that ancient man
was visited by extraterrestrials
in the deep past. It was written by Erich Von Daniken
in 1968, and became an international bestseller
which was followed by a string of books on the same topic.
The book takes examples from ancient monuments, carvings, paintings, and writings to prove that alien astronauts guided ancient man. The examples range from buildings that supposedly could only be built with alien technology to images that could only be representations of alien astronauts.
I read the book myself in my youth, and was quite impressed. However, as I got older, I realized that man’s ingenuity was nearly infinite, and to simply assume that artifacts like the pyramids were built with alien assistance because you couldn't believe a group of "primitive" people could do it on their own was cultural arrogance. There is also a theory growing in credence that these artifacts Von Daniken has ascribed to extraterrestrials are really the jetsam of an advanced civilization that existed prior to ours that was destroyed in the cataclysm that marked the end of the last ice age. This theory and arguments supporting it can be found in the book Fingerprints of the Gods by Graham Hancock.