moundbuilders. they made a country club golf course on mounds

using the mounds for bank shots, tricky chips. once every eighteen years

 when the full moon rises it floats above the center of the earthworks. 

eighteen holes in the earth to sink little white balls to reach in and

 retrieve and play through.

they called the course the moundbuilders, said they were preserving it.

if they move it they'll have to call it something else, they can't recreate

 the mounds, it'd be a different course.