Monona Mound is a Native American earthwork in Monona, Wisconsin, distinguished by an unusual club shape with a conical end and long linear tail. Built by Late Woodland people sometime between about 700 and 1100 A.D., it once stood as part of a small group with another club-shaped mound and two conical mounds, all since destroyed except this one. Its alignment may have held ceremonial or calendrical meaning, matching the sunset on the first or second day after the spring equinox. Preserved on private property through the Reindahl family’s stewardship, it later became the first mound protected under Wisconsin’s Burial Sites Preservation Act and was listed on the National Register of Historic Places in 1989.