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anon?
my initial thought which I continue to believe, is that it is some kind of arena for a human hunting or gladiator game.
appears to be only one way in and out.
Berms are use to restrict area and allow viewing.
they are already priming us for this bloodsport
https://www.mirror.co.uk/news/weird-news/hunting-humans-set-become-big-8244649
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it was an sports arena.
the berm served a dual purpose.
Limit the play area and provide a viewing platform
you don't need a berm for a tennis court. A fence is what is used.