Those who watch TV channels that delve into pseudoscience -- such as The Learning Channel (TLC) -- or love to visit fringe theory web sites, must have encountered Erich von Daniken or his web site.

Von Daniken's theory is that ancient astronaut aliens visited Earth several times, and interacted with several civilization. The traces of these visits are everywhere, from ancient Peru to ancient Egypt.

It is interesting that the concept of the Ancient Astronaut was popularized by the Egyptian well known writer and columnist, Anis Mansour, in his book "Those who came from the sky" الذين هبطوا من السماء

The Hall of Maat covers the Ancient Astronaut theory on their web site.

Others have also written specifically on Von Daniken, for example, the Skeptic Dicitonary and the Debunker.