@ChrisAine That was the odd bit, they didn't look like they were a cut and polish job but rather just precision cut and we don't have the ability to cut rounded corners like that with saws, even lasers which could cut those corners would have left pitting. It's more like the stones were cut with a variation on a CNC machine but one that could work with large blocks of basalt and other stones on that hardness scale.

@ChrisAine Perhaps with the most basic and simple of tools, lots and lots of people and lots and lots of time. You can wear down the biggest rock just by rubbing away endlessly, and if they were a seasonal farming economy, then they probably had long periods where they had thousands of people with nothing to do, and it was actually a problem for the govenments to find things for them to do.

@ChrisAine In the end you have to explain where those super intelligent beings came from. If you make something up without evidence it really explains nothing. The things you see and do not understand do not qualify as evidence.