Illinois - Significance region: Local
| Knobeloch-Seibert Farm |
| Knox County Courthouse and Hall of Records |
| Knox County Jail |
| Knuessl Building |
| Kosciuszko Park Field House |
| Krause Music Store |
| K-Town Historic District |
| Kuppenheimer, Louis B., Jr., House |
| La Grange Village Historic District |
| LaHarpe City Hall |
| LaHarpe Historic District |
| Lake Bluff Uptown Commercial Historic District |
| Lake Ellyn Park |
| Lake Forest Cemetery |
| Lake-Side Terrace Apartments |
| Lakewood Balmoral Historic District |
| Lamoine Hotel |
| Lamont, Robert P., House |
| Lampert-Wildflower House |
| Laramie State Bank Building |
| Larkin Home for Children |
| Larson, Mads C., House |
| LaSalle City Building |
| LaSalle Downtown Commercial District |
| LaSalle Street Auto Row Historic District |
| Laurent, Kenneth and Phyllis, House |
| Lawrence County Courthouse |
| Lawson, Victor F., House YMCA |
| Lazy A Motel |
| Leaning Tower of Niles, The |
| LeClaire Historic District |
| LeClaire Hotel |
| Legler, Henry E., Regional Branch of the Chicago Public Library |
| Lemont Downtown Historic District |
| Lemont Methodist Episcopal Church |
| Lena Water Tower |
| Leonard, Clifford Milton, Farm |
| LeRoy Commercial Historic District |
| Lesem, S.J., Building |
| Lewis Round Barn |
| Liberty Theater |
| Libertyville Downtown Historic District |
| Libertyville High School Brainerd Building |
| Libertyville Town Hall |
| Library-University of Illinois at Urbana-Champaign |
| Lilacia Park Historic District |
| Lincoln Branch Peoria Public Library |
| Lincoln Building |
| Lincoln Colored Home |
| Lincoln Public Library |
| Lincoln (Statue) |
| Lindemann and Hoverson Company Showroom and Warehouse |
| Linden Avenue Terminal |
| Linn, Howard and Lucy, House |
| Litchfield Elks Lodge No. 654 |
| Litchfield Public Library |
| Little Beaver Site |
| Livingston County Courthouse |
| Logan Square Boulevards Historic District |
| Lone Tree School |
| Loop Retail Historic District |
| Loucks, Charles N., House |
| Louisville and Nashville Depot |
| Lou Mitchell's Restaurant |
| Lowell Park |
| Lumber Exchange Building and Tower Addition |
| Lumpkin Heights and Elm Ridge Subdivision Historic District |
| Lundberg, Charles, House |
| Lynch, Timothy J., House |
| Lyndon Bridge |
| Macomb Courthouse Square historic District |
| Madison Theatre |
| Magill House |
| Magnolia Manor |
| Maid-Rite Sandwich Shop |
| Majestic Theatre |
| Malden Towers |
| Malvern Roller Mill |
| Mandel Brothers Warehouse Building |
| Mandel, Mr. Fred L., Jr., House |
| Manly-McCann House |
| Manor House |
| Manske-Niemann Farm |
| Marissa Academy |
| Mark, Caroline, House |
| Mark Twain Hotel |
| Marquette Apartments |
| Marshall Business Historic District |
| Marshall Field and Company Store |
| Marshall Hotel |
| Marshall Site |
| Martin House |
| Martin, Sarah, House |
| Mary A. Todd School |
| Marywood Academy |
| Masonic Temple |
| Masonic Temple Building |
| Masonic Temple Building |
| Mason, Paris, Building |
| Massie Variety Store |
Data from United States Park Service and Wikidata
