Marshall Site - Credit: Wikimedia Commons
The Marshall Site is an archaeological site in the Marshall State Fish and Wildlife Area in Marshall County, Illinois, across the Illinois River from Chillicothe. The site consists of a boulder carved with five petroglyphs. The petroglyphs, which archaeologists believe were created by Native Americans between 1673 and 1835, depict three anthropomorphs, an L-shaped figure, and a possible avimorph. The site was added to the National Register of Historic Places on August 25, 2014. Read more on Wikipedia
Source: en.wikipedia.org