Connecticut - Criteria: C (architecture/engineering)
| Abbott, George S., Building |
| Abington Congregational Church |
| Academy Hall |
| Acadian House |
| Agudath Sholem Synagogue |
| Alden Tavern Site |
| Aldrich Free Public Library |
| Alldis, James, House |
| Allen House, The |
| Allen Place-Lincoln Street Historic District |
| Allen's Cider Mill |
| Allis-Bushnell House |
| Allyn, Capt. Benjamin, II, House |
| Alsop, Richard IV, House |
| Ambassador Apartments |
| American Legion Forest CCC Shelter |
| American Mills Web Shop |
| American Thermos Bottle Company Laurel Hill Plant |
| American Thread Company |
| Ames, Winslow, House |
| Anderson, Leroy, House |
| Andover Center Historic District |
| Andrews, Luman, House |
| Andrews, Moses, House |
| Andrew, William, House |
| Ann Street Historic District |
| Anshei Israel Synagogue |
| Ansonia Library |
| Apartment at 49-51 Spring Street |
| Applewood Farm |
| Armstrong, M. and Company Carriage Factory |
| Armstrong Rubber Company Building |
| Arrawanna Bridge |
| Ashford Academy |
| Ashlawn |
| Aspetuck Historic District |
| Asylum Avenue District |
| Atwater, George, House |
| Atwater-Linton House |
| Atwater Manufacturing Company |
| Austin, A. Everett, House |
| Avery Homestead |
| Avery House |
| Avery, Thomas, House |
| Avon Congregational Church |
| Babb's Beach |
| Backus, Nathaniel, House |
| Bacon Academy |
| Bacon, Jabez, House |
| Baldwin, Amos, House |
| Baldwin, Caleb, Tavern |
| Baldwin, George, House |
| Baldwin, Timothy, House |
| Baldwin, Zaccheus, House |
| Ball and Roller Bearing Company |
| Baltic Historic District |
| Bank Street Historic District |
| Barber, Giles, House |
| Barbour, Lucius, House |
| Barker, John, House |
| Barkhamsted Center Historic District |
| Barlow, Aaron, House |
| Barnes-Frost House |
| Barnes, Selah, House |
| Barns, Acors, House |
| Barnum Museum |
| Barnum/Palliser Historic District |
| Bartlett, Daniel and Esther, House |
| Basset, Daniel, House |
| Bassickville Historic District |
| Batterson Block |
| Beach, Charles E., House |
| Beach, Samuel, House |
| Bean Hill Historic District |
| Beardsley, Capt. Philo, House |
| Beardsley-Mix House |
| Beardsley Park |
| Beaver Hills Historic District |
| Belden, Horace, School and Central Grammar School |
| Beleden House |
| Bellamy, Joseph, House |
| Belltown Historic District |
| Bemont, Makens, House |
| Benedict, Francis Jr., House |
| Benedict House and Shop |
| Benedict-Miller House |
| Beth El Synagogue |
| Beth Hamedrash Hagodol Synagogue |
| Beth Israel Synagogue |
| Beth Israel Synagogue |
| Bethlehem Green Historic District |
| Bigelow-Hartford Carpet Mills |
| Bigelow-Hartford Carpet Mills Historic District |
| Bikur Cholim Synagogue |
| Bill, Gurdon, Store |
| Bingham, Clarence A., School |
| Birmingham Green Historic District |
| Bishop, Peyton Randolph, House |
| Bishop, William D., Cottage Development Historic District |
| Bissell, Henry B., House |
Data from United States Park Service and Wikidata
