Connecticut - Criteria: C (architecture/engineering)
| Taylor Memorial Library |
| Taylor's Corner |
| Telephone Exchange Building |
| Temple Beth Israel |
| Temple Beth Israel |
| Temple Beth Israel |
| Tephereth Israel Synagogue |
| Terry-Hayden House |
| Terry's Plain Historic District |
| Terryville Waterwheel |
| Thames Shipyard |
| The Seaside |
| Thomaston Opera House |
| Thompson Hill Historic District |
| Thompson, William H., Farmstead |
| Thumb, Tom, House |
| Tiffany, Simon, House |
| Todd, Orrin, House |
| Tolland County Courthouse |
| Tolland Green Historic District |
| Tongue Point Lighthouse |
| Topsmead |
| Torringford Street Historic District |
| Torrington Fire Department Headquarters |
| Town Bridge |
| Town Farms Inn |
| Town Hall |
| Town Hall and District School No. 6 |
| Tranquility Farm |
| Treadway, Townsend G., House |
| Treadwell House |
| Trinity Church |
| Trinity Church |
| Trinity Church |
| Trinity Methodist Episcopal Church |
| Trowbridge Square Historic District |
| Trumbull, John, Birthplace |
| Tully, William, House |
| Tunxis Forest Headquarters House |
| Tunxis Forest Ski Cabin |
| Tunxis Hose Firehouse |
| Turner, Dr. Philip, House |
| Turn-of-River Bridge |
| Tuttle, Bronson B., House |
| Twain, Mark, House |
| Tyler, John, House |
| Tyler, Solomon, House |
| Umpawaug District School |
| Uncasville School |
| Union Baptist Church |
| Union Church/St. Paul's Church |
| Union Depot |
| Union Green Historic District |
| Union School |
| Union Station |
| Union Village Historic District |
| Unitarian Meetinghouse |
| Unitarian-Universalist Church |
| United Bank Building |
| United Congregational Church |
| United Illuminating Company Building |
| United States Housing Corporation Historic District |
| United States Post Office and Court House |
| United States Post Office, Westport, Connecticut |
| University of Connecticut Historic District-Connecticut Agricultural School |
| Upper Albany Historic District |
| Upper Main Street Historic District |
| Upper State Street Historic District |
| U.S. Post Office |
| U. S. Post Office and Federal Building |
| US Post Office-Ansonia Main |
| US Post Office-Bridgeport Main |
| US Post Office-Greenwich Main |
| US Post Office-Manchester Main |
| US Post Office-Meriden Main |
| US Post Office-Milford Main |
| US Post Office-Naugatuck Main |
| US Post Office-New London Main |
| US Post Office-Norwich Main |
| US Post Office-South Norwalk Main |
| US Post Office-Stamford Main |
| U.S.S. NAUTILUS (submarine) |
| Viets' Tavern |
| Villa Bella Vista |
| Villa Friuli |
| Village Creek |
| Wadsworth Atheneum |
| Wadsworth Estate Historic District |
| Waldo, Edward, House |
| Wallingford Center Historic District |
| Wallingford Railroad Station |
| Wall Street Historic District |
| Walnut Grove |
| Walnut Hill District |
| Walnut Hill Park |
| Ward-Heitman House |
| Ward, William, Jr., House |
| Warner House |
| Warner, Jonathan, House |
| Warner Theatre |
Data from United States Park Service and Wikidata
