English: Visiting University of Wisconsin-Madison artist-in-residence Ute Ritschel from Germany surveys the bird effigy mound on Observatory Hill, Madison, Wisconsin. Located on the campus of the University of Wisconsin-Madison, with a commanding view of Lake Mendota, are two effigy mounds: a bird and a two-tailed water spirit (also interpreted as a turtle). The wings of the bird, shown here, have been shortened from their original span of 133 feet. A number of other mounds belonged to this group but have been destroyed. To the south, several conicals were eliminated when Agriculture Hall was built in 1902. And to the north, a panther effigy and a linear mound were destroyed by the university sometime after 1922. The effigies were built during the period of Late Woodland culture (650-1200) and were later used by the Winnebago people for ceremonies and burials. The two surviving mounds were added to the National Register of Historic Places in 2004.