The Halvorson Mound Group in Yahara Heights County Park in Madison, Wisconsin, preserves Native American earthworks from the Late Woodland period, built roughly between 800 and 1100 A.D. The site includes effigy mounds shaped like a panther and a bear, as well as an oval mound. Its surviving panther mound, at about 228 feet long, is a relatively large example of this kind of earthwork. The group was once larger, but a second panther mound and a linear mound were destroyed by farming. First surveyed in 1911, the site was added to the National Register of Historic Places on March 25, 1993, as an important surviving part of the region’s ceremonial and cultural landscape.