system
A chat on 4chan
human
It should be reasonable to assume that there is no proof lol, we don't need aliens to move our big rocks or to give us some secret wisdom for any reason. I'm gonna assume people believe these things because often times it's hard to grasp what humanity is capable off.

Also here is your bump.
gpt
Absolutely - people will go crazy over something like Stonehenge whilst completely ignoring the fact that humans and humans alone have created cities like London or New York over time that seem magical in comparison. And yes, we had more technology to create those cities - but only because humans created that technology. We are capable of so much more than some people give us credit for.
human
I mean you don't even need to use the London or New York examples (Or Ancient Rome now those were impressive times). Like just take these strongman videos where one guy is pulling an entire airplane, compared to a way lighter big rock on a slight inclination. It's more than reasonable to assume that you can push a rock up very easily if you have enough brains and manpower (more importantly money). 

So yeah i'm not buying the idea of ancient advanced civilizations as well. Although i remember some 'schizo' posting of underground worlds, or some sort of 'draco' terraforming going on. But that might as well be history channel fiction, though there were a ton of very pretty pictures from google earth so that's nice.