Indiana - Area of significance: Architecture
| Lodge |
| Log Cabin Inn Tourist Camp |
| Lombard Building |
| Long Schoolhouse |
| Lords, William L., House |
| Lowell Commercial Historic District |
| Lowell Heights-Olivet African Methodist Episcopal Church |
| Lowry, William, House |
| Luick, William Henry, Farmhouse |
| Lusk Home and Mill Site |
| Maack, Albert, House |
| Madden School |
| Madison Historic District |
| Maier, Peter Augustus, House |
| Majestic Building |
| Major, Daniel S., House |
| Makepeace, George, House |
| Mallon Building |
| Manche, Maurice W., Farmstead |
| Manchester Apartments |
| Mansion Row Historic District |
| Maple Grove Campground |
| Maple Grove Road Rural Historic District |
| Marcy Village Apartments |
| Marian Apartments |
| Maring, Grace Keiser, Library |
| Marion Branch, National Home for Disabled Volunteer Soldiers Historic District |
| Marion Downtown Commercial Historic District |
| Marion Firestone Auto Supply & Service Center |
| Marion PCC & St. Louis Railroad Depot |
| Markle House and Mill Site |
| Marktown Historic District |
| Marott Hotel |
| Marott's Shoes Building |
| Marquette School |
| Marr, James, House and Farm |
| Marshall County Court House |
| Marshall County Infirmary |
| Marshall, Thomas R., School |
| Mars Theatre |
| Martens |
| Martin Place Historic District |
| Martinsville Commercial Historic District |
| Martinsville High School Gymnasium |
| Martinsville Northside Historic District |
| Martinsville Sanitarium |
| Martinsville Vandalia Depot |
| Masonic Temple |
| Masonic Temple |
| Masonic Temple |
| Masonic Temple |
| Massachusetts |
| Massachusetts Avenue Commercial District |
| MATERIAL SERVICE (shipwreck) |
| Matthews Stone Company Historic District |
| Mattison, Donald M., House |
| Mayfield, Leroy, House |
| Mayleeno |
| McCallum, William, House |
| McClain, John W., House |
| McClelland-Layne House |
| McColloch-Weatherhogg Double House |
| McCormack-Bowman House |
| McCormick, Charles, Building |
| McCormick's Creek State Park Entrance and Gatehouse |
| McCurdy Building (Sears, Roebuck and Company Building) |
| McCurdy Hotel |
| McDoel Historic District |
| McDonald, James and Lucinda, House |
| McGill, Charles S. and Mary, House |
| McHaffie, Melville F., Farm |
| McJohnston Chapel and Cemetery |
| McKay |
| McKinley School |
| McNamee-Ford House |
| Meeks Avenue Historic District |
| Meier, George Philip, House |
| Melodeon Hall |
| Memorial Park |
| Merchants National Bank and Annex |
| Meridian-Forest Historic District |
| Meridian Park Historic District |
| Merit-Tandy Farmstead |
| Merom-Gill Township Carnegie Library |
| Merrifield-Cass House |
| Messick Masonic Temple |
| Metamora Historic District |
| Meyer, Dr. John and Gerda, House |
| Meyer, Joseph Ernest, House |
| M. Fine & Sons Building |
| Miami County Courthouse |
| Michael, Enos, House |
| Michigan City Breakwater Light |
| Michigan City East Pierhead Light Tower and Elevated Walk |
| Michigan City Lighthouse |
| Michigan City Post Office |
| Middletown Commercial Historic District |
| Milan Masonic Lodge No. 31 |
| Milford, Marshall M., House |
| Milisen, Dr. Robert L. and Ellen, House |
Data from United States Park Service and Wikidata
