ferretbacon
Obsessor
Well, I mean...
Note the squared-off sides. It's almost definitely a Cahokia mound, maybe Monk's Mound when you consider the (anachronistic) stone steps:
Spoiler :
I agree. This seems like the obvious and closest match. I think it's definitely a Cahokia mound, either a Monk's Mound wonder or, perhaps, an improvement from a new Cahokia city state.
If it was a motte and bailey, where's the keep at the top of the hill? I also don't think it looks much like a Maori pa from the images I've looked up.