[throwaway787544]

Whoever built them, it's clear it wasn't one people at one time. The architecture diverges quite a bit, the same way nearly all cultures' architecture evolved. Some walls are rough and patched together, some are uniform, some have right angles, some have no right angles, some have gaps, some have no gaps, the sizes and materials vary. You see the same thing from the Mycenaeans and other prehistoric peoples (who also built massive temples and cities out of variously constructed boulders) as their building methods changed.