"Fingerprints of the Gods' By Grahm Hancock
I forced my way through that as a 4th grader to prove that I could read nonfiction. Did you (with a significantly greater knowledge base than I had) find it believable? I can't for the life of me remember if it qualifies as 'conspiracy theory' worthy.
Also, I'm reading 'Atlas Shrugged' again, and finding a lot of little jabs at communism that I missed the 1st time.