Indiana - Criteria: C (architecture/engineering)
| Lake County Sheriff's House and Jail |
| Lake County Tuberculosis Sanatorium Nurses Home and Superintendent's House |
| Lake Ditch Bridge |
| Lake Erie and Western Depot Historic District |
| Lakeside Historic District |
| Lakeville High School |
| Lamb's Creek Bridge |
| Landers, Franklin-Black and Adams Farm |
| Landing, The, Historic District |
| Lane, Henry S., House |
| Lanier Mansion |
| LaSalle Annex |
| LaSalle Hotel |
| La Salle Street Bridge |
| Laughery Creek Bridge |
| Laurel and Prospect District |
| Lauter, H., Company Complex |
| Lawton, Chauncey N., House |
| Learner Building |
| Leatherwood Station Bridge |
| Leedy, Bert, Round Barn |
| Leeper Park |
| Leeper, Samuel, Jr., House |
| Leesburg Historic District |
| Legg House |
| Lehmback, Charles, Farmstead |
| Leich, Charles, and Company |
| Leive, Parks and Stapp Opera House |
| Leland Hotel |
| Lemmon's Church and Cemetery |
| Lenhart Farmhouse |
| Lentz House (Hotel Sheller) |
| Lerner Theatre |
| Levey, Louis, Mansion |
| Lewis, Thomas J., House |
| Liberty Baptist Church |
| Liberty Courthouse Square Historic District |
| Liberty Residential Historic District |
| Liberty Township Schoolhouse No. 2 |
| Ligonier Historic District |
| Lilly Biological Laboratories |
| Lincoln Boyhood National Memorial |
| Lincoln Park School |
| Lincolnshire Historic District |
| Lincoln Street Historic District |
| Lindenwood Cemetery |
| Lindley, Thomas Elwood, House |
| Linton Commercial Historic District |
| Linton Public Library |
| Linwood Colonial Apartments |
| Little Cedar Grove Baptist Church |
| Littleton, Frank, Round Barn |
| Lockefield Garden Apartments |
| Lockerbie Square Historic District |
| Lockheed PV-2 Harpoon No. 37396 |
| Lockyear College |
| Lodge |
| Lombard Building |
| Long Schoolhouse |
| Lords, William L., House |
| Lowell Commercial Historic District |
| Lowry, William, House |
| Luick, William Henry, Farmhouse |
| Lusk Home and Mill Site |
| Maack, Albert, House |
| Madden School |
| Madison County Bridge No. 149 |
| Madison Historic District |
| Maier, Peter Augustus, House |
| Majestic Building |
| Major, Daniel S., House |
| Makepeace, George, House |
| Mallon Building |
| Manche, Maurice W., Farmstead |
| Manchester Apartments |
| Mansfield Bridge |
| Mansion Row Historic District |
| Maple Grove Road Rural Historic District |
| Marble Creek Bridge |
| Marcy Village Apartments |
| Marian Apartments |
| Maring, Grace Keiser, Library |
| Marion County Bridge 0501F |
| Marion Downtown Commercial Historic District |
| 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 Bridge |
| 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 |
Data from United States Park Service and Wikidata
