Maine - Area of significance: Architecture
| Hutchins House |
| Hutchins, Moses, House |
| Hyde Mansion |
| Indian Island Light Station |
| Indian River Baptist Church |
| Influence, The |
| Ingalls House |
| Ingraham, Charles H., Cottage |
| Ingraham, Joseph Holt, House |
| Intervale Farm |
| Irish, J. & O., Store |
| Isaacson, Philip M. and Deborah N., House |
| Isle Au Haut Light Station |
| Islesboro Free Library |
| Isles of Shoals |
| Jackson, Dr. F. W., House |
| Jacobs Houses and Store |
| Jacobson, Pehr J., House |
| Jarvis, Col. Charles and Mary Ann, Homestead |
| Jay-Niles Memorial Library |
| Jefferson Town House |
| Jellison, Theodore, House |
| Jenkins, Charles W., House |
| Jesup Memorial Library |
| Jewett-Eastman House |
| Jewett, Sarah Orne, House |
| Jonas Cutting-Edward Kent House |
| Jonesboro Union Church |
| Jordan, Charles A., House |
| Jordan, F.M., House |
| Jordan School |
| Jordon, Col, Meltiah, House |
| Journal Building |
| Kane, John Innes, Cottage |
| Kavanagh, Gov. Edward, House |
| Kellogg, Elijah, Church |
| Kennebec County Courthouse |
| Kennebec River Light Station |
| Kennebunk High School |
| Kennebunk Historic District |
| Kennebunkport Historic District |
| Kennebunk River Club |
| Kent's Hill School Historic District |
| Kezar Falls Circulating Library |
| Kineo Cottage Row Historic District |
| King, Gov. William, House |
| Kinsley, Martin, House |
| Knight-Corey House |
| Knowlton, Ebenezer, House |
| Knowlton, Jabez, Store |
| Knox County Courthouse |
| Kora Temple |
| Kresge Building |
| Kromberg Barn |
| Lady Pepperrell House |
| Lamb Block |
| Lancaster Block |
| Land's End Historic District |
| Larsson-Noak Historic District |
| Laudholm Farm |
| Lawrence Library |
| Leavitt, A. B., House |
| Leavitt, James, House |
| Lee, Jesse, Church |
| Leighton, Adam P., House |
| Lewiston City Hall |
| Lewiston Commercial Historic District |
| Lewiston Mills and Water Power System Historic District |
| Lewiston Public Library |
| Lewiston Trust and Safe Deposit Company |
| Libby-Hill Block |
| Libby-MacArthur House |
| Libby's Colonial Tea Room |
| Liberty Hall |
| Lightship No. 112, NANTUCKET |
| Limington Academy |
| Limington Historic District |
| Lincoln House |
| Lincoln School |
| Lincoln Street Fire Station |
| Lincoln Street Historic District |
| Lincolnville Center Meeting House |
| Lisbon Falls High School |
| Lithgow House |
| Lithgow Library |
| Little, Edward, House |
| Littlefield-Chase Farmstead |
| Littlefield-Dustin Farm |
| Littlefield Homestead |
| Littlefield-Keeping House |
| Littlefield Tavern |
| Little River Light Station |
| Lockwood Mill Historic District |
| Lombard, Alvin O., House |
| Long, Zadoc, Free Library |
| Lord Block |
| Lord, Capt. Nathaniel, Mansion |
| Lord-Dane House |
| Lord Farm |
| Lord, James C., House |
Data from United States Park Service and Wikidata
