Portions of two large ancient mound groups are preserved on the hospital grounds located on the north shore of Lake Mendota. The Farwell’s Point Mound Group includes a number of large conical or round mounds, part of a linear mound, and a bird effigy. They evidently were built over a thousand-year period. The large conical mounds are believed to have been built during the Middle Woodland Stage, about two thousand years ago, whereas the bird effigy and some other low mounds are characteristic of those built by the so-called effigy mound culture of the Late Woodland stage, around 700 to 1100 CE.
The Mendota State Hospital Mound Group is located east of this first group and contains some of the finest and largest effigy mounds preserved anywhere. Included are three large, straight-winged bird effigies (one with a 624-foot wing span), two panthers representing water and the underworld (one with an unusual curved tail), two bears, and a deer. The deer effigy is unusual because the builders depicted all four legs, instead of the usual two in profile. Visitors should check in at the hospital administration building to view the mounds.