Wikipedia claims that the Great Pyramid of Giza stood 146.6 meters tall when the Egyptians built it in 2570bce.
Convinced this was a myth, I headed outside and attempted to construct such a pyramid of my own. After over ten minutes of trying, however, my attempt at a perfect replica was still under two meters heigh. Thus, we now have scientific proof that the Great Pyramid of Giza does not exist, or that if it does, it's a lot shorter than they claim.
Another myth busted. Now where's my tv series?