Have you ever heard of the TV show Ancient Aliens? The show airs on the History Channel and claims that the reason for many of the feats of the ancient world (the pyramids of Egypt, the advanced culture of the Mayans, the Roman Empire, the Great Wall of China and much more) are the result of the visitation by super-intelligent extraterrestrial beings. At certain times in the show, there will be some claims that make logical sense, however absolutely nothing is tested scientifically and the majority of the show is based on hunches and far-fetched logical connections. Once the principles for scientific thinking are applied, it is very difficult to believe any of the claims made on the show. First, it is impossible to disprove the visitation of extraterrestrials thousands of years ago. Additionally, there are numerous other hypotheses that could account for the advanced technologies that existed in ancient times. Moreover, the claim that ancient aliens were running rampant in the early years of civilization is a very, very extraordinary claim, yet there is no solid evidence presented to back it up. And don't forget to apply Occam's razor; the simplest explanation would most likely not include stories of intergalactic space travel. I find these shows interesting and their attempts to connect ancient marvels to aliens are sometimes shockingly convincing, however, as stated above, there is simply no credibility when thinking scientifically.
Check out this link to read all about the "evidence" supporting Ancient Aliens: