This has been on the to-do list since last year. Yesterday. We checked it off the list.
Serpent Mound is an earthwork build by Indians 2000 years ago. It's a long mound shaped like a serpent, and it aligns (at many places) with special events like the sunrise/sunset of summer Equinox/solstice, etc. it doesn't look like much when you are walking alongside it.
But from above, it's impressive.
You can't even see the whole thing from his tower. Here's another view of what it looks like from far above:
Love when there's cool history so close to home!