Iowa - Criteria: C (architecture/engineering)
| Gaspard, D. Julius, House |
| Gehlen House and Barn |
| Geode State Park, Civilian Conservation Corps Area |
| GEO. M. VERITY |
| German Bank |
| German Bank Building of Walnut, Iowa |
| German Evangelical Reformed Church |
| Germania-Miller/Standard Hotel |
| German Methodist Episcopal Church |
| Gibbs, E. H., House |
| Gibson, E. R., House |
| Gilbert-Linn Street Historic District |
| Gilliece Bridge |
| Gingrich, Clement B., House |
| Gipple's Quarry Bridge |
| Glaspell, Isaac, House |
| Glenwood Archeological District |
| Glick-Sower House |
| Gobble and Heer-Spurgeons Building |
| Godard, Milton, House |
| Goddard Bungalow Court Historic District |
| Goering, Jacob, House |
| Goode, Lowry W., and Hattie N., First North Des Moines House |
| Goodnow Hall |
| Goodrich, William T., House |
| Gordon-Van Tine Company Historic District |
| Graceland Cemetery Chapel |
| Grace Methodist Episcopal Church |
| Grand Auditorium and Hotel Block |
| Grand Avenue Historic Commercial District |
| Grand Opera House |
| Grand River Bridge |
| Grand River Bridge |
| 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 |
| Great Northern Railway Steam Locomotive No. 1355 and Tender 1451 |
| 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 |
| Grimes Octagon Barn |
| 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 Corn Canning Co. |
| Guttenberg National Fish Hatchery and Aquarium Historic District |
| Guttenberg State Bank |
| Guy, Finley, Building |
| Haberkorn House and Farmstead |
| Hager, Otto J., House |
| Hale Bridge |
| Haley, F.E., Double House |
| Hallett Flat-Rawson & Co. Apartment Building |
| Hall, Hannah Morse Fowler, House |
| Hall, Israel, House |
| Hamburg Historic District |
| Hamburg Public Library |
| Hamilton Brothers Building |
| Ham, Mathias, House |
| Hammond Bridge |
| Hampton Double Square Historic District |
| Hancock, Charles T., House |
| Hancock County Courthouse |
| Haner, William, Polygonal Barn |
| 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 |
| Harvey Railroad Bridge |
| Hatton, Dr. John B. and Anna M., House |
| Hawkeye Creek Bridge |
| Hawkeye Insurance Company Building |
| Hawkeye Street Underpass |
| Hayes, William B., House |
| Haymarket Commercial Historic District |
| Hays, E. R., House |
| Hazen, Allen, Water Tower |
Data from United States Park Service and Wikidata
