Atop a plateau overlooking the Brush Creek Valley, Serpent Mound is the largest and finest serpent effigy in the United States. Nearly a quarter of a mile long, Serpent Mound apparently represents an uncoiling serpent. In the late 19th century, Harvard University archaeologist Frederic Ward Putnam excavated Serpent Mound and attributed the creation of the effigy to the builders of the two nearby burial mounds, which he also excavated. This, this culture is referred to as the Adena (800 BC–AD 100). A third burial mound at the park and a village site near the effigy's tail belong to the Fort Ancient culture (AD 1000–1550). A more recent excavation of Serpent Mound revealed wood charcoal that could be radiocarbon dated. Test results show that the charcoal dates to the Fort Ancient culture. This new evidence of the serpent's creators links the effigy to the elliptical mound and the village rather than the conical burial mounds. The head of the serpent is aligned to the summer solstice sunset and the coils also may point to the winter solstice sunrise and the equinox sunrise. Today, visitors may walk along a footpath surrounding the serpent. The museum contains exhibits on the effigy mound and the geology of the surrounding area.

The site offers exhibits and tours.