Iowa - Area of significance: Architecture
| Grand View College (Old Main) |
| Grandview Park Music Pavilion |
| Granger House |
| Grant Commercial Historic District |
| Grant, Douglas and Charlotte, House |
| Greater Second Street Historic District |
| Greek Orthodox Church of Saint George |
| Greene County Courthouse |
| Greenfield Public Square Historic District |
| Green, John A., Estate |
| Greenwood Cemetery Chapel |
| Greenwood Park Plats Historic District |
| Grilk, Charles, House |
| Grinnell Herald Building |
| Grinnell Historic Commercial District |
| Grinnell, Levi P., House |
| Griswold National Bank |
| Grotto of the Redemption |
| Grundy County Courthouse |
| Guiberson House |
| Gull Point State Park, Area A |
| Gull Point State Park, Area B |
| Guttenberg National Fish Hatchery and Aquarium Historic District |
| Guttenberg State Bank |
| Guy, Finley, Building |
| Haberkorn House and Farmstead |
| Hager, Otto J., House |
| Haley, F.E., Double House |
| Hallett Flat-Rawson & Co. Apartment Building |
| Hall, Hannah Morse Fowler, House |
| Hall, Israel, House |
| Hamburg Historic District |
| Hamburg Historic District |
| Hamburg Public Library |
| Hamilton Brothers Building |
| Ham, Mathias, House |
| Hampton Double Square Historic District |
| Hancock, Charles T., House |
| Hancock County Courthouse |
| Hansen, Andrew P., Farmstead |
| Hanson, Alfred, House |
| Hardacre Theater |
| Hardin County Courthouse |
| Hardware Building |
| Harker House |
| Harlan Courthouse Square Commercial District |
| Harmon and LeValley Northwest Historic District |
| Harper and McIntire Company Warehouse |
| Harrison County Courthouse |
| Harrison, E. H., House |
| Harris Wagon and Carriage Shop |
| Hart, Charles Walter, House |
| Harvat, Emma J., and Mary E. Stach House |
| Hatton, Dr. John B. and Anna M., House |
| Hawkeye Insurance Company Building |
| Hayesville Independent School |
| Hayes, William B., House |
| Haymarket Commercial Historic District |
| Hays, E. R., House |
| Hazen, Allen, Water Tower |
| Hebard, Alfred, House |
| Hebert, Louis, House |
| Hedge Block |
| Heinz, Bonaventura, House (second) |
| Henderson, Daniel and Nancy Swaford, House |
| Henne, Robert, House |
| Henn Mansion |
| Henry County Courthouse |
| Henry County Savings Bank |
| Henryson, Henry T. and Emilie (Wiese), House |
| Henshie-Briggs Row House |
| Henyon-Kasper-Duffy Barn |
| Heritage Hill Historic District |
| Herman, John H., House |
| Herndon Hall |
| Herring Motor Car Company Building |
| Herschler, Christian and Katharina, House, Barn and Outbuildings Historic District |
| Hibernia Hall |
| Hickman-Nietert-Odd Fellows Building |
| Highland Historic District |
| Highland Park Historic Business District at Euclid and Sixth Avenues |
| Highlandville School |
| Hiller Building |
| Hillside |
| Hippee Building |
| Historic Railroad District |
| Hitchcock, Rev. George B., House |
| Hoag, J. J., House |
| Hobson Block |
| Hoersch, John, House |
| Hoffman Building |
| Hoffman, Phil, House |
| Hoffman, Samuel, Jr., House |
| Hofmann Building |
| Hohberger Building |
| Holbrook, William, House |
| Holdoegel, Perry C. and Mattie Forrest, House |
| Holland, Ora, House |
| Hollenfelz House |
| Holmes, John S. and Elizabeth Beem, Barn |
Data from United States Park Service and Wikidata
