Ohio - Significance region: Local
| Krumberg, Theodore, Building |
| Krumm House |
| Kuebeler, August, House |
| Kuebeler-Stang Block |
| Kuenzer, Joseph II, House |
| Kuhns, Benjamin F., Building |
| Kulas, E. J., Estate Historic District |
| Kumler, Elias, House |
| Kundtz, Theodor, Company Building |
| Kunkle Log House |
| Labold House and Gardens |
| Ladd's Tavern |
| Lafayette Lodge No. 79 |
| Lafee Building |
| Lagonda National Bank |
| Lakefork School |
| Lake Hamilton Dam |
| Lake Ridge Island Mounds |
| Lake Shore and Michigan Southern (LS&MS) Railroad Depot-Wauseon |
| Lake Shore and Michigan Southern RR Depot and Freight House |
| Lake Shore Bank and Cleveland Public Library St. Clair Branch |
| Lake Shore & Michigan Southern Railroad Station |
| Lake Township School |
| Lakewood Downtown Historic District |
| Lamberson-Markley Houses |
| Lambert, Jeremiah, House and Barn |
| Lambert-Parent House |
| Lancaster Historic District |
| Lancaster West Main Street Historic District |
| Landen Mounds I and II |
| Landers Brothers Company Building |
| Landes, Samuel, House |
| Landmark Tavern |
| Landt Building |
| Lane, Ebenezer, House |
| Lane-Hooven House |
| Lane's Mill Historic Buildings |
| Langdon House |
| Lange Hotel |
| Lanman-Ingram House |
| Lanning, T., & Co. Department Store |
| Lansdowne House |
| Lanterman Mill |
| Lasalle, Koch and Company Department Store |
| LaSalle Theater Building |
| Lash, William D., House |
| La Tosca Flats |
| Latty, Judge Alexander, House |
| Laughlin, Homer, House |
| Laundon, Thomas W., House |
| La Ventura Apartments |
| Lavin, Carl and Audrey, House |
| Law, Henry, Farm Historic District |
| Lawndale Farm Complex |
| Lawrence, William, House |
| Layman, Christopher C., Law Office |
| Lay, Samuel, House |
| Lea Block |
| Lebol, John, House, Smokehouse and Springhouse |
| Lee, Samuel, House |
| Leesville Town Hall |
| Leftwich House |
| Legal Arts Centre |
| Lehman, Abraham, Farmhouse |
| Lehman, John H., High School |
| Leipsic City Hall |
| Leist, John, House at Dutch Hollow |
| Leppert, C., Barn |
| Leppert, C., Cabin |
| Leppert, C., Farm |
| Lerner Building |
| Lersch, John, House |
| Levering Hall |
| Levy, Harry Milton, House |
| Lewis, Dr. A. C., House |
| Lewis, Samuel, Farmhouse |
| Lewis, Samuel, House |
| L. Hoster Brewing Company |
| Libbey, Edward Drummond, High School |
| Liberty Theatre |
| Lichliter Mound And Village Site |
| Ligget, J., Residence |
| Liggett-Freedlander House |
| Light, Jacob, House |
| Lilienthal Building |
| Lilley, Robert D., House |
| Lillybanks |
| Lilly House |
| Lima Cleaning and Pressing Company |
| Lima Memorial Hall |
| Lima Pennsylvania Railroad Passenger Depot |
| Lima Stadium |
| Limbach Block Historic District |
| Limestone Vale |
| Linaweaver, Dr. Albert, House |
| Lincoln Theatre |
| Lind Arcade |
| Linden Community and Recreation Center |
| Lindner Building |
| Lindsey Building |
Data from United States Park Service and Wikidata
