Connecticut - Area of significance: Architecture
| Sprague, Elias, House |
| Spring Hill Historic District |
| Stackpole, Moore, and Tryon Building |
| Stafford Hollow Historic District |
| Stafford Springs Historic District |
| St. Andrew's Episcopal Church |
| St. Andrew's Protestant Episcopal Church |
| Stanley-Whitman House |
| Stanley-Woodruff-Allen House |
| Stanton, Robert, House |
| Stapleton Building |
| Starr, C. J., Barn and Carriage House |
| Starr Mill |
| State Arsenal and Armory |
| State Park Supply Yard |
| St. Benedict's Church |
| Steamboat Dock Site |
| Steele, Allyn, House |
| Sterling Block-Bishop Arcade |
| Sterling Hill Historic District |
| Sterling Hill Historic District |
| Sterling Homestead |
| Stevens, William, House |
| Stick Style House at Stony Creek |
| St. James' Episcopal Church |
| St. John's Episcopal Church |
| St. John's Episcopal Church |
| St. John's Episcopal Church |
| St. John's Protestant Episcopal Church |
| St. Luke's Chapel |
| St. Luke's Episcopal Church |
| St. Mark’s Episcopal Church |
| St. Mary's Church |
| St. Mary's Parochial School |
| Stoddard, Capt. Mark, Farmstead |
| Stoeckel, Robbins, House |
| Stone, Medad, Tavern |
| Stonington Borough Historic District |
| Stonington Harbor Lighthouse |
| Stonington High School |
| Stony Creek-Thimble Islands Historic District |
| Stony Hill School |
| St. Paul's Methodist Episcopal Church |
| St. Peter's Episcopal Church |
| Stratfield Historic District |
| Stratford Center Historic District |
| Strickland Road Historic District |
| Strong House |
| Strouse, Adler Company Corset Factory |
| Sts. Cyril and Methodius Church |
| Sturges, Jonathan, House |
| Sturges-Wright House |
| Suburban Club |
| Suffield Historic District |
| Sumner-Carpenter House |
| Sunny Ridge Historic District |
| Sun Terrace |
| Swain-Harrison House |
| Swallen, James, House |
| Sweetland, Sophia, House |
| Swift, M. and Sons Company |
| System House |
| Taftville |
| Talcottville Historic District |
| Tamarack Lodge Bungalow |
| Tariffville Historic District |
| Tarrywile |
| Tatum, Corinne and George Liston Jr., House |
| 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 |
| The Seaside |
| Thomaston Opera House |
| Thompson Hill Historic District |
| Thompson, William H., Farmstead |
| Thumb, Tom, House |
| Tiffany, Simon, House |
| Titicus Hill Historic District |
| Todd, Orrin, House |
| Tolland County Courthouse |
| Tolland Green Historic District |
| Topsmead |
| Torringford Street Historic District |
| Torrington Fire Department Headquarters |
| 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 College Long Walk Historic District |
Data from United States Park Service and Wikidata
