The Robert Allerton Park is a 1,517-acre (614 ha) park, nature center, and conference center located in the rural Piatt County township of Willow Branch, near Monticello, Illinois on the upper Sangamon River. The park and manor house, The Farms, are attributed to owner Robert Allerton, industrialist heir, artist, art collector and garden designer. Robert and his adopted son John Gregg Allerton donated the complex to the University of Illinois in 1946.