How were the mounds built?
Some mounds were built by piling and packing dirt on the ground surface into the desired shape. Other mounds were built on a prepared ground surface. Care was taken to strip away the sod in the area where the mound would be constructed. Yet other mounds were dug in the shape of an effigy and then piled with dirt so that half of the mound is below the ground and the other half is above. Mounds were built in a variety of shapes and sizes. The largest known hemispherical mound was built in Richland County, Wisconsin and was approximately 200 feet in diameter. Near to that mound was the largest recorded bird effigy mound with a wingspan of nearly a quarter mile. Unfortunately, both the bird and the hemispherical mound have been destroyed. The largest extant bird effigy mound is located on the grounds of the Mendota State Hospital on the north side of Lake Mendota in Madison, with a wingspan of 624 feet. The longest recorded linear embankments were located along Lake Monona and measured 700