Colorado - Criteria: C (architecture/engineering)
| Hotel de Paris |
| Hotel Jerome |
| Hotel Meeker |
| Hotel St. Regis |
| House at 1750 Gilpin Street |
| Hoverhome and Hover Farmstead |
| Hover, W.A., and Company Building |
| Howard Store |
| Hudson, Sim, Motor Company |
| Huerfano Bridge |
| Huerfano County Courthouse and Jail |
| Huerfano County High School |
| Hugo Municipal Pool |
| Humboldt Street Historic District |
| Humphrey House |
| Hungarian Freedom Park |
| Husung Hardware |
| Hyman-Brand Building |
| Hynes, Thomas, House |
| I and M Building |
| Idaho Springs Downtown Commercial District |
| Ideal Building |
| Iglesia de San Francisco de Assisi |
| Iliff Hall |
| Inspiration Point |
| Interlaken Resort District |
| IOOF Hall |
| Jackson, F.A., House |
| Jackson, George, House |
| Jacoe Store |
| Jaffa Opera House |
| Jamaica Primary School |
| Jamestown Mercantile Building |
| Jamestown Town Hall |
| Jefferson Denver South Park and Pacific Railroad Depot |
| Joshel, Lloyd M., House |
| Kauffman House |
| Kauffman, William, House |
| Keating, Jeffery and Mary, House |
| Keck Homestead |
| Keithley Log Cabin Development District |
| Kelley-McDonald House |
| Kennicott Cabin |
| Kerr House |
| Kettle-Jens House |
| Key Savings and Loan Association Building |
| Keystone Hotel |
| King, Dr. Alexander T., House and Carriage House |
| Kinner, John, House |
| Kissock Block Building |
| Kistler-Rodriguez House |
| Kittredge Building |
| Knearl School |
| Knight-Wood House |
| Kohn House |
| Kopper's Hotel and Saloon |
| Kullgren House |
| Labo Del Rio Bridge |
| Lackner's Tavern |
| La Fave Block |
| Lafayette House |
| La Jara Depot |
| Lake Agnes Cabin |
| Lake Haiyaha Trail |
| Land's End Observatory |
| Lang, William, Townhouse |
| Larimer Square |
| LaSalla House |
| Las Animas Post Office |
| Lathrop, J. V., House |
| Latuda, Frank, House |
| Laurel School Historic District |
| La Veta Pass Narrow Gauge Railroad Depot |
| Lay School |
| Leadville Historic District |
| Leadville National Fish Hatchery |
| Lebanon School |
| Leeman Auto Company Building |
| LeFevre, Owen E., House |
| Leiffer House |
| Lennox House |
| Lett Hotel |
| Lewis, A. T., New Building |
| Lewis Mill |
| Limon Railroad Depot |
| Lincoln School |
| Lincoln School |
| Lincoln School |
| Lindley-Johnson-Vanderhoof House |
| Little Buckaroo Ranch Barn |
| Little Church in the Pines |
| Little Estate |
| Little Thompson River Bridge |
| Littleton Creamery-Beatrice Foods Cold Storage Warehouse |
| Littleton Main Street |
| Littleton Town Hall |
| Logan County Courthouse |
| Loma Community Hall |
| Longmont Carnegie Library |
| Longmont College |
Data from United States Park Service and Wikidata
