Got it. So aliens built advanced civilizations able to harness the immense energies required for inter stellar flight, possibly invented and build hyperdrives, human stasis, tractor beams, travelled light years to find Earth so they can... cut and move some large-ish stones.
Is that the working theory?
What other explanation can there be...????
HUH????
Actually I think some of these could be a ‘marker’ for other civilizations.
They came here from Orion, so they laid out a structure in the shape of how Orion looks from here.
It is big so you can see it, if you are from another planted and are doing a look around this planet- they are easy to spot.
Just a working theory though