Poverty Point in Louisiana has six concentric rings of earthworks covering 150 hectares , built by hunter gatherers. We don't know the time scale but that is quite an area .
They ,All , laugh at me, when I say that I can detect, concentric circles, that go on for a very long way.
I will raise you your six American concentric rings, and go for two miles of concentric rings arouns Avebury.
K.
How can you be sure they were hunter gatherers? Were they perhaps fishermen or fish farmers? How mobile and how settled were they? How long would it have taken to construct the circles?