The two mounds at Fort Hill are the only remaining Native American mounds in Merton. During a survey of Merton in 1851, Increase Lapham found several other mound groups, including a very large bird-shaped effigy mound about 1/4 mile southeast of this site, but that mound and the other groups were destroyed by farming. Native Americans constructed the mounds from 700 BC to 1300 AD during the Woodland Period. Some mounds were used as burial places while others were not, and the purpose of the mounds on what Lapham called Fort Hill is unknown. Under Wisconsin law, Indian mounds are protected and are considered burial sites.