Pennsylvania - Area of significance: Architecture
| Langley High School |
| Lansdowne Park Historic District |
| Lansdowne Theatre |
| Lapp Log House |
| Larimer School |
| Larkin-Belber Building |
| Latimer School |
| Latrobe Armory |
| Laughlin, Hugh, House |
| Laurel Hill Cemetery |
| Laurel Hill RDA |
| Laurel-Rex Fire Company House |
| Lawndale School |
| Lawrence County Courthouse |
| Lawrence Park Historic District |
| Lawrence Public School |
| Lawrenceville Historic District |
| Lazaretto, The |
| Lea, Henry C., School of Practice |
| Leas, Benjamin B., House |
| Leaser, Frederick and Catherine, Farm |
| Lebanon Veterans Administration Hospital Historic District |
| Leedom, David, Farm |
| Lehigh Valley Railroad Headquarters Building |
| Lehigh Valley Silk Mills |
| Lehigh Water Gap Chain Bridge Toll House and East Bridge Abutment |
| Lehner Grain-and-Cider Mill and House |
| Leiby, Jacob, Farm |
| Leidy, Dr. Joseph, House |
| Leiper, Thomas, Estate |
| Lemington Elementary School |
| Lemont Historic District |
| Lemoyne, Dr. Julius, House |
| Lenhart Farm |
| Lerch Tavern |
| Letsche Elementary School |
| Levering, William, School |
| Lewisburg Armory |
| Lewisburg Historic District |
| Lewis, Evan, House |
| Lewistown Armory |
| Liberty Fire Company No. 5 |
| Liberty Hall |
| Liberty School No. 4, Friendship Building |
| Lightfoot Mill |
| Lightner, Isaac, House |
| Ligonier Armory |
| Ligonier Historic District |
| Lincoln Elementary School |
| Lincoln, Mordecai, House |
| Lincoln University |
| Linden Avenue School |
| Linden Grove Pavilion |
| Linden Hall at Saint James Park |
| Linden Hall Historic District |
| Linden House |
| Lindsey, Christiana, House |
| Linn Run State Park Family Cabin District |
| Lititz Moravian Historic District |
| Lits Department Store |
| Littell, David, House |
| Little Buffalo Historic District |
| Little, Moses, Tavern |
| Livingood House-Stryker Hospital |
| Llanerch Public School |
| Llyswen Historic District |
| Lochiel Farm |
| Locust Grove |
| Logan Demonstration School |
| Logan Furnace Mansion |
| Logans Ferry Powder Works Historic District |
| Log House, Hiester House, and Market Annex |
| Loleta Recreation Area |
| Longfellow, Henry, School |
| Longfellow School |
| Long-Hawerter Mill |
| Longland |
| Long Meadow Farm |
| Longue Vue Club and Golf Course |
| Longwell, David, House |
| Longwood Gardens District |
| Lorraine Apartments |
| Loutellus Apartment Hotel |
| Lovell Manufacturing Company |
| Lowell, James Russell, School |
| Lower Marsh Creek Presbyterian Church |
| Lower Merion Academy-Cynwyd Elementary School-Bala Cynwyd Junior High School Complex |
| Lower North Philadelphia Speculative Housing Historic District |
| Lower Swedish Cabin |
| Lowrie, Sen. Walter, House |
| Loyalhanna Lodge No. 275 |
| Ludlow, James R., School |
| Lukens Main Office Building |
| Lunn's Tavern |
| Lutz-Franklin School |
| Lutz, John F., Furniture Co. & Funerary |
| Luzerne County Courthouse |
| Luzerne Presbyterial Institute |
| Lynn Hall |
| Madison Elementary School |
Data from United States Park Service and Wikidata
