Well, if you're us. You go straight there the next day.
I give you Serpent Mound in Adams County Ohio. And ancient mound built by unknown people. The magazine they gave us at the welcome center says Serpent Mound is the "largest surviving example of prehistoric effigy mound in the world." I'm taking their word for it.
Serpent Mound isn't a burial mound, but this Adena mound just off the parking lot is one of the Native American burial mounds.
Andrew squinting in the sun.
This site also lines up with some cool astrological things. Including, according to the show, ancient alignment to the constallation Draconis.
It's hard to see but Serpent Mound is a huge mound shaped like a snake, it's tail coils on one end and it's mouth opens around an egg-shaped thing on the other.
Here is it's tail.
I doubt very much this site was built my aliens, and I think it's kind of an insult that the show implied that humans weren't capable of building this. There is no evidence of who or what culture built this site, but the conical burial mounds(first picture) are dated back to 800 BC. Which I think is pretty awesome. It's a completely different kind of history at this site and we have no idea who made it. I'm really glad we went to see it.