No one has ever explained to my satisfaction how people who couldn’t even smelt iron knew where the sun was going to shine on the solstices. I guess even that long ago, the ironworkers on Atlantis had a strong union. ;-)
That is elementary, my dear CholeraJoe. You can do it yourself, with nothing more than some stakes and a few years of observation. Just keep marking out where the shadow of a central stake falls, at about the same time of day.
Neolithic people were ignorant, not stupid.