Illinois - Criteria: C (architecture/engineering)
| Sears, Albert H., House |
| Second Presbyterian Church |
| Sentinel Building |
| Seventh Street Commercial Historic District |
| Seville Bridge |
| Shakespeare Garden |
| Shastid, John, House |
| Shaw-Van Gilder House |
| Shedd Park Fieldhouse |
| Sheffield Historic District |
| Shelbyville Historic District |
| Sheridan Park Historic District |
| Sheridan Plaza Hotel |
| Sheridan Square Apartments |
| Sherman Park |
| Sherrard Banking Company |
| Shiloh House |
| Shoreland Hotel |
| Shoreline Apartments |
| Shriver Farmstead |
| Shriver House |
| Sigma Alpha Epsilon Fraternity House |
| Silhan, Mr. Robert, House |
| Silversmith Building |
| Singer Building |
| Sixth, Seventh, and Tenth Street Stone Arch Bridges |
| Skinner, Richard M., House |
| Slaten-LaMarsh House |
| Sloane, William and Jennette, House |
| Small-Towle House |
| Smith-Duncan, House and Eastman Barn |
| Smith, Ephraim, House |
| Smith, J. P., Shoe Company Plant |
| Smith, Tina Weedon, Memorial Hall |
| Snite, John Taylor, House |
| Snowden, Elsworth, House |
| Soffel, Albert, House |
| Solon, Francis and Abbie, House |
| Somerset Hotel |
| Soule, C. S., House |
| Soulsby Service Station |
| South Charter Street Historic District |
| South Dearborn Street-Printing House Row Historic District |
| South Fulton Churchhouse |
| South Henderson Church and Cemetery |
| South Loop Printing House District |
| South Park Manor Historic District |
| South Shore Beach Apartments |
| South Shore Bungalow Historic District |
| South Shore Country Club |
| South Side German Historic District |
| South Side School |
| Spafford, Amos Catlin, House |
| Sparta Historic District |
| Spiegel Office Building |
| Spivey Building |
| Sprague's Super Service |
| Springdale Cemetery |
| Spring-Douglas Historic District |
| Spring Valley House-Sulfur Springs Hotel |
| Squires, Frederick, House |
| S.R. Crown Hall |
| Standard Oil Gasoline Station |
| Standard Oil Gasoline Station |
| St. Anne's Episcopal Church |
| Stapleford-Hover-Whitney House |
| Starved Rock Lock and Dam Historic District |
| Starved Rock Lodge and Cabins |
| State Bank |
| State Bank Building |
| State Savings Loan and Trust |
| Stauduhar House |
| St. Charles Hospital |
| St. Charles Municipal Building |
| Stearns-Wadsworth House |
| Steffens, Joseph, House |
| Stephenson, Benjamin, House |
| Stephenson County Courthouse |
| Sterling Masonic Temple |
| Steuben Club, The |
| Stevens House |
| Stevenson, Adlai E., I, House |
| Stevenson, Adlai E., II, Farm |
| Steward, Lewis, House |
| Stickney, George, House |
| St. Ignatius College |
| Stinson Memorial Library |
| St. James Catholic Church and Cemetery |
| St. James Episcopal Church |
| St. James Episcopal Church |
| St. Johns Episcopal Church |
| St. Louis Street Historic District |
| St. Luke's Hospital Complex |
| St. Mary's Church |
| St. Mary's Church of Gilberts |
| St. Matthew Evangelical Lutheran School |
| St. Nicholas Hotel |
| Stolp Island Historic District |
| Stone Arch Bridge |
| Stoneleigh Manor |
Data from United States Park Service and Wikidata
