The Adena culture was a Pre-Columbian Native American culture that existed from 800 BC to 1 AD, in a time known as the Early Woodland period. The Adena culture refers to what were probably a number of related Native American societies sharing a burial complex and ceremonial system. The Adena culture was centered on the location of the modern state of Ohio, but also extended into contiguous areas of northern Kentucky, eastern Indiana, West Virginia, and parts of extreme western Pennsylvania.
Lasting traces of Adena culture are still seen in the remains of their substantial earthworks. At one point, larger Adena mounds numbered in the hundreds, but only a small number of the remains of the larger Adena earthen monuments still survive today. These mounds generally ranged in size from 20 feet (6.1 m) to 300 feet (91 m) in diameter and served as burial structures, ceremonial sites, historical markers, and possibly gathering places. These earthen monuments were built using hundreds of thousands of baskets full of specially selected and graded earth. According to archaeological investigations, Adena earthworks were often built as part of their burial rituals, in which the earth of the earthwork was piled immediately atop a burned mortuary building. These mortuary buildings were intended to keep and maintain the dead until their final burial was performed. Before the construction of the earthworks, some utilitarian and grave goods would be placed on the floor of the structure, which was burned with the goods and honored dead within. The earthwork would then be constructed, and often a new mortuary structure would be placed atop the new earthwork. After a series of repetitions, mortuary/earthwork/mortuary/earthwork, a quite prominent earthwork would remain. In the later Adena period, circular ridges of unknown function were sometimes constructed around the burial earthworks.