INTERLAKEN, Switzerland — Long before the "X-Files" craze and talk of alien abductions, when man was preparing his first trip to the moon, a Swiss hotel manager came up with a theory that earthly civilization began with extraterrestrial visits thousands of years ago.
Ridicule from scientists notwithstanding, Erich von Daeniken sold 60 million books in 32 languages and made "Chariots of the Gods" part of the ufologists' lexicon.
Thirty-five years on, the fascination endures. There are plans for a 22-part TV series called "Chariots of the Gods -- The Mysteries Continue." And von Daeniken's ancient astronauts are set to make a permanent landing in a scenic Alpine valley with this weekend's opening of the world's only theme park devoted to historic wonders like the Egyptian pyramids and future unknowns like the conquest of Mars.
"Imagine you are back in ancient Egypt," von Daeniken declared during a tour of the disused airfield in Interlaken where he has built the park.
The great pyramid of Giza was larger than the cathedrals of Milan, Rome and Florence put together, he said. Why and how were 2.5 million stone blocks piled up, the largest weighing 400 tons? Who built the pyramids, apart from Pharaoh Cheops, who only reigned for 20 years and whose mummy has not been found?
"There are lots of questions, but you won't get any answers out of us," von Daeniken, short, stocky and suntanned, concluded in winding up a well-practiced routine.
A 68-year-old grandfather who enjoys cooking and French wine in his home in the Alpine village of Beatenberg, von Daeniken said he first got the idea for his Mystery Park 20 years ago.
He says he wants visitors to experience firsthand the sense of "wonder and astonishment" that inspired him to write "Chariots of the Gods" in 1966 while he was managing a luxury hotel.
"I claim that our forefathers received visits from the universe in the remote past ... that these strangers annihilated part of mankind existing at the time and produced a new, perhaps the first, Homo sapiens," he wrote in the foreword to the book.
Von Daeniken, who skipped university and served a couple of short stints in prison for fraud, backed up his ideas with detailed scientific "facts" and archeological theories based on his study of pyramids, ancient ruins and lost cities.
The book was published in 1968 and caused a sensation -- "a work of monumental importance ... which has withstood the test of time," Amazon.com says.
His theories about the origin of modern man brought him into conflict with the Roman Catholic Church and his argument in general was derided by scientists. But readers -- especially in the United States and Germany -- loved them. Book followed book, allowing him to proclaim himself the best-selling nonfiction writer of all time.
His most recent title, "The Gods Were Astronauts," published in 2001, explores the great world religions, their myths and belief structures in an attempt to discover who or what were the gods described in ancient stories. His conclusion is that they were extraterrestrials who left traces of their presence everywhere on Earth.
Von Daeniken says the forthcoming TV series combines "the suspenseful investigative techniques of 'CSI,' melds it with the exotic adventures of 'Alias,' and then throws in a dash of 'Tomb Raider' for good measure."
Despite the huge public success, critics continue to pan his theories.
"These mythologizations are so silly; they are easily disproved and rather embarrassing," said David Brin, an astronomer and science fiction writer who writes about the possibility of life elsewhere.
"These people hate the open scientific discourse that has developed with the vast spread of education. They want secrets, ancient or modern, that only they know," Brin added.
Von Daeniken dismisses such criticism as pure jealousy. He cites a string of honorary doctorates and other awards from around the world as proof that he is taken seriously. He also trumpets his archeology and astronautics research association, which publishes "Legendary Times," a newsletter devoted to his ancient astronaut theory.
He shows no sign of slowing down, saying his lecture appearances and research take him an estimated 100,000 miles a year.
He retains an adoring following.
"You helped me so much, to open my eyes to all the truth forgotten in time, all the truth about our past," Diana Al Hazard from Paris wrote in one of dozens of Happy 68th Birthday messages posted on von Daeniken's Web site. "I thank you so much for everything. You really fulfilled your mission on this planet."
Other readers, however, said they enjoyed the books but took the theories with a grain of salt.
"I've been interested in such 'blue sky' stories for decades, but never fell for the extrapolations of old Erich," said Jack Greenfield, 68, a public relations consultant in New York. "He made a lot of money and I suppose gave many of us a good deal of exciting reading pleasure and food for thought.
"Trouble is, nothing he said, as far as I can tell, was ever even distantly related to truth."