Extraterrestrial visitations from prehistoric times to the present

Erich von Daeniken has a very interesting approach to investigating the origins of the human race (do we come from the outer space?). He is not an educated archaeologist - he is an hotelier with great interest in history of human race, of its origins. He is ready to travel wherever there is something interesting to be seen and not yet fully explained by contemporary science. He does not claim that what he says is the truth (unlike many people who write these sorts of alternative-history books) - he only raises questions, brings forth very interesting findings