Serpent Mound is an ancient effigy mound located in Adams County, Ohio. It is shaped like a serpent with an undulating body and a coiled tail, stretching about 1,348 feet long. The mound is believed to have been constructed by indigenous peoples, possibly the Adena or Fort Ancient cultures, around 1000 to 300 BCE. The purpose of Serpent Mound remains a topic of debate among archaeologists. Some theories suggest it may have been used for ceremonial purposes or as an astronomical observatory, aligning with celestial events. Today, it is a protected historical site and a popular destination for visitors interested in ancient Native American cultures.