Connecticut - Significance region: Local
| Canoe Brook Historic District |
| Capewell Horse Nail Company |
| Capron-Phillips House |
| Captain Nathan Hale Monument |
| Carpenter House |
| Carroll Building |
| Carter, Hubbell, House |
| Case Brothers Historic District |
| Cassidy House |
| Castle, Dr. Andrew, House |
| Catlin, J. Howard, House |
| Centerbrook Congregational Church |
| Chaffee, Hezekiah, House |
| Chandler, Capt. Seth, House |
| Chapin, Philip, House |
| Chapman, David, Farmstead |
| Charlton, Capt. Richard, House |
| Charter Oak Bank Building |
| Charter Oak Firehouse |
| Charter Oak Place |
| Chatfield Farmstead |
| Chevry Lomday Mishnayes Synagogue |
| Christ Episcopal Church and Tashua Burial Ground |
| Church Farm |
| Church of the Holy Trinity and Rectory |
| Clark, Andrew, House |
| Clark, Avery, House |
| Clark Brothers Factory No. 1 |
| Clark Brothers Factory No. 2 |
| Clark Homestead |
| Cogswell, Edward, House |
| Colebrook Store |
| Commerce Street Historic District |
| Commercial Trust Company Building |
| Comstock, Abijah, House |
| Comstock-Cheney Hall |
| Cone, Jared, House |
| Congress Street |
| Cook, John, House |
| Cos Cob Railroad Station |
| Cosier-Murphy House |
| Cossitt, Frederick H., Library |
| Coult, Abraham, House |
| Cove Island Houses |
| Cowles, Capt. Josiah, House |
| Curtis Memorial Library |
| Curtis, Nathaniel, House |
| Curtiss, Reuben, House |
| Cypress Cemetery |
| Darling Family Farmstead and Tavern |
| Darling, James Alexis, House |
| Darling, Robert and Julia, House |
| Davenport, Deacon John, House |
| Davenport, Hanford, House |
| Day, Amasa, House |
| Day, Calvin, House |
| Day House |
| Deep River Town Hall |
| Dickerman II, Jonathan, House |
| Dillon Building |
| Downtown North Historic District |
| Dudley Farm Historic District |
| Dudley, Jedidiah, House |
| Eagle's Nest |
| East District School |
| East Haven Green Historic District |
| East Haven High School |
| Edgerton |
| Edward Bloom Silk Company Factory |
| Ein Jacob (Ayn Yacob) Synagogue |
| Elam Ives House |
| Eliot, Jared, House |
| Eliot, Samuel, House |
| Elliottville Lower Mill |
| Elmore Houses |
| Ely, Rev. John, House |
| Emmanuel Church |
| Enfield Carnegie Library |
| Enfield Town Meetinghouse |
| Engine Company 15 Fire Station |
| Engine Company 16 Fire Station |
| Engine Company 1 Fire Station |
| Engine Company 2 Fire Station |
| Engine Company 6 Fire Station |
| Engine Company 9 Fire Station |
| Eno Memorial Hall |
| Esperanza |
| Evans, Ebenezer, House |
| Fairfield Railroad Stations |
| Fanning, Capt. Thomas, Farmstead |
| Ferris, Samuel, House |
| Filley, Capt. Oliver, House |
| First Baptist Church |
| First Congregational Church of East Hartford and Parsonage |
| First Lutheran Church of the Reformation |
| Fish, Abel H., House |
| Fitch, John, School |
| Five Mile Point Lighthouse |
| Florence Mill |
| Forbes, Samuel, Homestead |
Data from United States Park Service and Wikidata
