Iroquois County Illinois has 6 places on the National Register of Historic Places including 1 place of Statewide significance. Significant places include Old Iroquois County Courthouse, Prairie Dell Meetinghouse, Smith, A. Herr and E. E., Public Library, St. Mary's Church and Watseka Union Depot.
Some of the country's most noteable architects helped create the Iroquois County places including A.C. Mantor, C.B. Leach, Paul O. Moratz, Joseph Molitor and Fred E. King. Prominent architectural styles found in Iroquois Country are Romanesque, Tudor Revival and Italianate.