The saw kerfs and hole saw cuts in granite should all be made to some common dimension. Designed tooling has to have some commonality. But I don't think the meter would be used 12000, 24000, 36000 years ago unless those kerfs and holes we see today were exact metric dimensions. Granite saw marks indicating 20 foot diameter and a 3mm kerf are impossible even today. The feedrate of hope sawed granite at 1mm per revolution is impossible today too. Has anyone really put it all together?

I'm talking pre-egyptian, pre-stonehenge, precision machined megalithic stuff.