We know that our ancient ancestors were skilled builders and exceptionally gifted craftspeople. The evidence of that is everywhere, from the tiniest pieces of jewelry they made to the enormous cities they created. What we're less sure of is how they went about some of these construction tasks. Some of the things made by people living thousands of years ago ought not to have been possible with the technology of the time, and yet they were made nonetheless. Scientists struggle to explain some of the mysteries you're about to see, so see if you can come up with explanations of your own!