Ohio - Criteria: C (architecture/engineering)
| Kenilworth Avenue Historic District |
| Kennedy Apartments and Commercial Block |
| Kennedy Stone House |
| Kennel, John, Jr., Farm |
| Kennel, John Sr., Farm |
| Kent, Charles House |
| Kent Industrial District |
| Kent Jail |
| Kent, J., Residence |
| Kenton-Hunt Farm |
| Kenton Public Library |
| Kenyon College |
| Kern, Rufus A., House |
| Kerr, Benjamin F., House |
| Kestler Building |
| Keyt, Gideon, House |
| Kidwell Covered Bridge |
| Kies, Lewis, House |
| Kilbourn Commercial Building |
| Kilpi Hall |
| Kimball, Addison, House |
| Kimball House |
| Kimball, Lemuel II, House |
| Kindleberger, Frederick, Stone House and Barn |
| Kindra, W. H., Apartments |
| King, Ahimaaz, House |
| King, Dr., House |
| King-Phillips-Deibel House |
| King, William, House |
| Kingwood Center |
| Kinney, Eli, House |
| Kinney, James, Farmstead |
| Kirby, James, Mill |
| Kirby, Josiah, House |
| Kirby Road School |
| Kirker Covered Bridge |
| Kirkwood, Joseph, House |
| Kirtland Temple |
| Kiser Mansion |
| Klaus Block |
| Knapp, William, House |
| Knowlton, Dr. William A., House |
| Knox County Courthouse |
| Koehne-Poast Farm |
| Kokosing House |
| Kossuth Colony Historic District |
| Krause, John, House |
| Krippendorf-Dittman Company |
| Krippendorf Estate |
| Kroger Barnes Graf, Gretchen, House |
| Krug House |
| Krumberg, Theodore, Building |
| Krumm House |
| Kuebeler, August, House |
| Kuebeler-Stang Block |
| Kuenzer, Joseph II, House |
| Kuhns, Benjamin F., Building |
| Kumler, Elias, House |
| Kunkle Log House |
| Labold House and Gardens |
| Lafayette Lodge No. 79 |
| Lagonda Club Building |
| Laird Hall |
| Lakefork School |
| Lake Hamilton Dam |
| Lake Shore and Michigan Southern (LS&MS) Railroad Depot-Wauseon |
| Lake Shore And Michigan Southern Passenger Depot |
| Lake Shore And Michigan Southern Railroad Depot |
| 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 |
| Lamberson-Markley Houses |
| Lambert-Parent House |
| Lancaster Historic District |
| Landes, Samuel, House |
| Landt Building |
| Lane, Ebenezer, House |
| Lane-Hooven House |
| Langdon House |
| Lanning, T., & Co. Department Store |
| 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 |
| Laurel Homes Historic District |
| Lawndale Farm Complex |
| Layman, Christopher C., Law Office |
| Lay, Samuel, House |
| Lea Block |
| Lebanon Cemetery Entrance Arch |
| Lebanon Cemetery Superintendent's House |
| Lebol, John, House, Smokehouse and Springhouse |
| Leftwich House |
| Lehman, Abraham, Farmhouse |
| Lehman, John H., High School |
Data from United States Park Service and Wikidata
