Back in the early 1970's there was a very popular book called "Chariots of the Gods?" by Erich von Daniken. He claimed aliens had been here and had left such evidence as...uh, well, read it if you want.
Like anything else with aliens, debunkers came swarming to defend the faith. Here is one example.
Anyway, I figured it was probably about the 30th anniversary by now and I looked it up for blogfodder. And now I find that someone is making it into a TV series.
If you like oddball stuff like this, you'll like Charles Fort and Art Bell. If you don't, you're more likely to like James Randi.