Maine - Significance region: Local
| Saco City Hall |
| Saco High School (old) |
| Saco Historic District |
| Sagamore Village Historic District |
| Sail Loft |
| Saint Mary's General Hospital |
| Saint Saviour's Episcopal Church and Rectory |
| Salem Town House (Former) |
| Salmon Falls (East) Historic District |
| Salmon Falls (West) Historic District |
| Sanford Mills Historic District |
| Sangerville Town Hall |
| Sargent, Daniel House |
| Sargent-Roberts House |
| Savings Bank Block |
| Scarborough High School |
| Schlotterbeck and Foss Building |
| Scribner Homestead |
| Sea Change |
| Seal Harbor Congregational Church |
| Searsport Historic District |
| Seaverns, George, House |
| Seavey, A. B., House |
| Seavey-Robinson House |
| Seawall Campground |
| Second Callahan Block |
| Second Congregational Church |
| Security Trust Building |
| Sedgwick Historic District |
| Sellers, Salome, House |
| Seven Star Grange, No. 73 |
| Sewell Memorial Congregational Church |
| Shaw, William M., House |
| Shore Acres |
| Singhi Double House |
| Skelton, Thomas, House |
| Skowhegan Free Public Library |
| Skowhegan Historic District |
| Slate House |
| Small Point Club |
| Smith-Emery House |
| Smith, George W., Homestead |
| Smith, Parson, House |
| Smith, Zebulon, House |
| Snipe Farm |
| Sodergren, John J. and Martha, Homestead |
| Soderholtz, Eric E., Cottage |
| Soldiers Memorial Library |
| Somerset Academy |
| Somerset County Courthouse |
| Somesville Historic District |
| Sorrento Library |
| Sound Schoolhouse |
| Southard Block |
| South Berwick Village Historic District |
| South Bridgton Congregational Church |
| Southgate Farm |
| South Solon Meetinghouse |
| South Street Historic District |
| Sparrow House |
| Spaulding House |
| Spiller Farm Paleoindian Site |
| Spite House |
| Springdale Farm |
| Springfield Congregational Church |
| Sproul Homestead |
| Sproul's Cafe |
| Spruce Point Camps |
| Sprucewold Lodge |
| Spurwink Congregational Church |
| Squire Tarbox House |
| Stage Island Monument |
| Standish Corner Historic District |
| St. Andre's Parish |
| St. Anne's Church and Mission Site |
| St. Anne's Episcopal Church |
| Stanwood Homestead |
| Star of Hope Lodge |
| St. David Catholic Church |
| Stearns Hill Farm |
| St. Edward's Convent, (Former) |
| Steep Falls Library |
| Stetson Union Church |
| Stewart Free Library |
| St. Hyacinth School and Convent |
| Stimson Memorial Hall |
| St. James Episcopal Church |
| St. John Catholic Church |
| St. John's Catholic Church |
| St. John's Episcopal Church |
| St. Joseph's Academy and Convent-Catherine McAuley School |
| St. Joseph's Catholic Church |
| St. Lawrence Church |
| St. Mark's Episcopal Church |
| St. Mary's-By-The-Sea |
| St. Mary's Church |
| Stone Barn Farm |
| Stone, Capt. Nataniel, House |
| Stone, Elisha F., House |
| Stone House |
Data from United States Park Service and Wikidata
