Science does not have an answer for everything. That's the case for things which are happening in the world right now, and it's also the case for things that happened in the world thousands of years ago. They don't like to talk about it, but there are many ancient sites and structures all over the planet that were built with human hands, but scientists just can't tell us how such remarkable building work was accomplished using the tools available at the time. Let's take a look at some of the most outstanding examples!