I've often thought a race of huge "people" were the ones who built the pyramids and other monoliths around the globe. How did average sized people move hundreds of tons of stone? Giants could do that, though, but where are their bones? Surely some giants had to have died while here or were they taken away in their space craft? Why are monoliths all over the world, China, South America, Great Britian, Egypt, and on and on. Were they building societies and cities for their own population or did they build cities and then populate them with their own offspring? Lots of questions, yet no easy answers.