Connecticut - Criteria: C (architecture/engineering)
| Restmore |
| Revonah Manor Historic District |
| Reynolds Bridge |
| Richardson, Nathaniel, House |
| Rider, John, House |
| Ridgebury Congregational Church |
| Ridgefield Center Historic District |
| Rising Sun Tavern |
| River Park Historic District |
| River Road-Mead Avenue Historic District |
| River Road Stone Arch Railroad Bridge |
| Riverside Avenue Bridge |
| Riverside Cemetery |
| River Street Historic District |
| Riverton Historic District |
| Robbins, John, House |
| Robbins, Unni II, House |
| Robinson, P., Fur Cutting Company |
| Rock Hall |
| Rock Ledge |
| Rockville Historic District |
| Rockwell House |
| Rockwell Park |
| Rockwell, Solomon, House |
| Rocky Hill Center Historic District |
| Rocky Hill Congregational Church |
| Rogers, John, House |
| Root, Jonathan, House |
| Rosemary Hall |
| Rossie Velvet Mill Historic District |
| Round Hill Historic District |
| Route 146 Historic District |
| Rowe and Weed Houses |
| Roxbury Center |
| Rumsey Hall |
| Russell Company Upper Mill |
| Russell, Edward Augustus, House |
| Russell, Samuel Wadsworth, House |
| Russian Village Historic District |
| Rye House |
| Sabbathday House |
| SABINO (steamer) |
| Sage-Kirby House |
| Saint Anthony Hall |
| Saint Luke's Home for Destitute and Aged Women |
| Salem Historic District |
| Salem School |
| Salisbury Center Historic District |
| Sanford-Curtis-Thurber House |
| Sanford, Frederick S., House |
| Sanford-Humphreys House |
| Sanford Road Historic District |
| Sanseer Mill |
| Saugatuck River Bridge |
| Saugatuck River Railroad Bridge |
| Saxony Mill |
| Saybrook Breakwater Lighthouse |
| Schlaraffia Burg |
| Schoverling, Carl F., Tobacco Warehouse |
| Scoville Memorial Library |
| Scoville Powerhouse |
| Seaside Institute |
| Seaside Park |
| Seaside Village Historic District |
| Second Church of Christ |
| Sedgwick, Maj. Gen. John, House |
| Seelye, Seth, House |
| Selleck, Sylvanus, Gristmill |
| Seventh Sister |
| Seymour, Elisha, Jr., House |
| Seymour High School and Annex |
| Shade Swamp Shelter |
| Shambaugh House |
| Sharon Historic District |
| Sharon Valley Historic District |
| Shaw Mansion |
| Sheffield Street Bridge |
| Shelley House |
| Shelton, William, House |
| Shepard, John, House |
| Sherman, David, House |
| Sherman Historic District |
| Silvermine Center Historic District |
| Simpson, Dr. Frank T., House |
| Simpson, Samuel, House |
| Simsbury Bank and Trust Company Building |
| Simsbury Center Historic District |
| Simsbury Railroad Depot |
| Simsbury Townhouse |
| Sisson-South Whitney Historic District |
| Skee's Diner |
| Skelton, Dr. Henry, House |
| Skilton Road Bridge |
| Skinner, Jason, House |
| Slater Library and Fanning Annex |
| Sleeping Giant Tower |
| Sloan-Raymond-Fitch House |
| Sloper-Wesoly House |
| Smith, H. D., Company Building |
| Smith, Jabez, House |
Data from United States Park Service and Wikidata
