Poverty Point is a National Monument and World Heritage Site.
At the time Stonehenge was built natives in Louisiana hauled 2,000,000 cubic yards of soil and shaped them into a 72 foot tall mound and enormous half circles. The soil was dug and carried by hand, no domestic animals or wheeled carts. It was a staggering undertaking and to this day nobody knows why they did it.
After all that work the area was abandoned around 1100 BC.
Mound A
HAPPY TRAILS, STEVE