The Great Mound

Among the ten earthwork formations in Mounds State Park, there is only one Great Mound—appropriately named. Earthworks are monumental structures built from shaped earth, often used by ancient cultures for ritual, burial, or astronomical purposes. The Great Mound is the largest in Indiana, a circular enclosure nearly a quarter mile in circumference, with an embankment rising nine feet high.

Over time, theories about its purpose ranged from burial site to religious amphitheater, with some even suggesting Egyptian builders, a lost tribe of Israel, or ancient astronauts. Archaeological evidence, including charcoal remains, dates the mound to roughly 160–120 B.C., placing it in the pre-Columbian era and attributing its construction to the Adena culture, famed for their earthworks across Ohio, West Virginia, and beyond.

Today, the Great Mound is believed to be part of a vast astronomical alignment. From its center, the sun sets directly over nearby Fiddleback Mound on the summer solstice, while the winter solstice, equinoxes, and several bright stars could also be tracked from this vantage point.