Did aliens help build the Pyramids & other monuments? Or does the "ancient astronauts" idea go back to Swiss author Erich von Daniken, whose books challenge religion and science? Who were his enemies? What were his influences? Why was he jailed?

Discover some of America's most infamous cults. Whether its religious fire-and-brimstone, Armageddon, or visitors from outer space, the US has no shortage of like-minded people coming together to get swept up in the fervor.