Connecticut - Criteria: A (event)
| Glenville School |
| Glover House |
| Glover, John, House |
| Goffe Street Special School for Colored Children |
| Goodman, Timothy, House |
| Goodspeed Opera House |
| Goodwin Block |
| Gorton, William, Farm |
| Goshen Historic District |
| Grace Church Rectory |
| Grandview Terrace Boulevard |
| Graniteville Historic District |
| Great Captain Island Lighthouse |
| Greeneville Historic District |
| Greenfield Hill Grange #133 |
| Greens Ledge Lighthouse |
| Greenwich Town Hall |
| Greenwich YMCA |
| Greenwood Avenue Historic District |
| Groton Bank Historic District |
| Grove Street Cemetery |
| Haddam Center Historic District |
| Hadlyme Ferry Historic District |
| Hall-Benedict Drug Company Building |
| Hall, Isaac Davis and Marion Dalton, House |
| Hallville Mill Historic District |
| Halpine, J. S., Tobacco Warehouse |
| Hamburg Bridge Historic District |
| Hamden Bank & Trust Building |
| Hamden High School |
| Hamden Memorial Town Hall |
| Hamilton Park |
| Hammanasset Paper Mill Site |
| Hampton Inn |
| Harrison, Thomas, House |
| Hartford Colony |
| Hartford Golf Club Historic District |
| Hartford National Bank and Trust |
| Hartford & New Haven Railroad Depot |
| Hartford & New Haven Railroad-Freight Depot |
| Hartford Seminary Foundation |
| Hartford Union Station |
| Hart's Corner Historic District |
| Harvey, William H., House |
| Hastings Hill Historic District |
| Hathaways Store |
| Hattertown Historic District |
| Haviland and Elizabeth Streets-Hanford Place Historic District |
| Hayden, Capt. Nathaniel, House |
| Hazardville Historic District |
| Hebron Center Historic District |
| Hempstead Historic District |
| Hempstead, Joshua, House |
| Hempsted, Nathaniel, House |
| Higganum Landing Historic District |
| Highland Historic District |
| High Street Historic District |
| Hill's Academy |
| Hilltop Farm |
| Hine-Buckingham Farms |
| Hitchcock-Schwarzmann Mill |
| Hoadley, Isaac, House |
| Hoadley, John, House |
| Hoadley, Orrin, House |
| Hodges Square Historic District |
| Hollister, Homestead, The |
| Home Woolen Company |
| Hooker, Sarah Whitman, House |
| Hose and Hook and Ladder Truck Building |
| Hosmer, Daniel, House |
| Hotchkissville Historic District |
| Hotel America |
| Housatonic Railroad Station |
| Housatonic River Railroad Bridge |
| House at 111 Maple Avenue |
| House at 130 Hayden Station Road |
| House at 130 Mohegan Avenue |
| House at 161 Damascus Road |
| House at 29 Flat Rock Road |
| House at 44 Court Street |
| House at 736 Palisado Avenue |
| House at 847 Main Street, North |
| Howd, Eliphalet, House |
| Hoyt-Burwell-Morse House |
| Hunt, Dr. Chester, Office |
| Huntington Center Historic District |
| Huntington Street Baptist Church |
| Hurwood Company |
| Imperial Granum-Joseph Parker Buildings |
| Indian Harbor Yacht Club |
| Indian Hill Avenue Historic District |
| Israel Putnam School |
| Ivoryton Historic District |
| Jail Hill Historic District |
| Jerome, William I, House |
| Jones, Theophilus, House |
| Jordan Village Historic District |
| Keeler Tavern |
| Kelsey, Enoch, House |
| Kensington Soldier's Monument |
Data from United States Park Service and Wikidata
