Earthworks
Prehistoric Earthworks Travel Suggestions
The eastern U.S. has several prehistoric earthwork sites. Unlike the megaliths of Europe and East Asia, these become overgrown with vegetation and their once-distinct shapes fade. But once you appreciate what they are, they can become quite impressive.
Nonsensical pseudoarchaeology is deeply racist. It insists that non-European cultures were all "too primitive" to have done anything. They must have been helped by extraterrestrials, or widely wandering Egyptians, Phoenicians, and so on. Fantastic Archaeology describes and debunks the fakes and bigots.