Iowa - Area of significance: Architecture
| Business Part of Olin Historic District |
| Butterworth, Nathaniel, House |
| Byfield, Dr. Albert Henry, House |
| Calder Houses |
| Calhoun County Courthouse |
| Calvary Baptist Church/First Baptist Church |
| Cameron, W. S., House |
| Camp Harlan-Camp McKean Historic District |
| Cannon, Amaziah and Cornelia (Wait), House |
| Cannon, Wilbur D. and Hattie, House |
| Canton School |
| Carey, John T. and Marietta (Greek) House |
| Carnegie-Ellsworth Public Library |
| Carnegie Library |
| Carnegie Library Building |
| Carnegie-Stout Public Library |
| Carroll City-Mount Olivet Cemetery |
| Carr, William V., House |
| Carson, Thomas C., House |
| Carter House |
| Case, Hosea S. and Elizabeth, House |
| Case, Larnerd, House |
| Cass County Court House |
| Cassel, Carl and Ulrika Dalander, House |
| Castle Terrace Historic District |
| Cathedral Historic District |
| Cattermole Memorial Library |
| Cavanaugh-Zetek House |
| Caviness, Carl L., Post 102, American Legion |
| Cavin, Thomas E., House |
| Cawley, James, House |
| C B & Q Passenger Depot |
| Cedar County Sheriff's House and Jail |
| Cedar Falls Independent Order of Odd Fellows |
| Cedar Falls Post Office |
| Cedar Rapids Central Business District Commercial Historic District |
| Cedar Rapids Post Office and Public Building |
| Cedar Valley Seminary |
| Central City Commercial Historic District |
| Central Office Building |
| Central Park-North Main Street Historic District |
| Central School |
| Central School |
| Central Vinton Residential Historic District |
| Chaffee-Hunter House |
| Champlin Memorial Masonic Temple |
| Chan-Ya-Ta Site |
| Chapple and Young Block |
| Chariton Cemetery Historic District |
| Chariton City Hall and Fire Station |
| Chariton Free Public Library |
| Chariton Herald-Patriot Building |
| Chariton Masonic Temple |
| Charles City Junior-Senior High School |
| Chase, Charles F. and and Ruth, House |
| Chautauqua Park Historic District |
| Chautauqua Park Historic District |
| Cherokee Commercial Historic District |
| Cherry Bank |
| Chevra B'nai Yisroel Synagogue |
| Chicago and North Western Office Building/Passenger Depot-Lake City |
| Chicago and North Western Passenger Depot |
| Chicago, Burlington and Quincy Depot |
| Chicago, Burlington and Quincy Railroad-Creston Station |
| Chicago, Burlington and Quincy Station |
| Chicago, Milwaukee, and St. Paul Railroad-Grafton Station |
| Chicago, Milwaukee, St. Paul and Pacific Railroad Company Depot |
| Chicago, Milwaukee & St. Paul Depot-Jefferson |
| Chicago, Milwaukee, St. Paul & Pacific Combination Depot-Hornick |
| Chicago, Milwaukee, St. Paul & Pacific Depot-Delmar |
| Chicago & Northwestern Passenger Depot and Baggage Room-Carroll |
| Chicago, Rock Island and Pacific Railroad-Grinnell Passenger Station |
| Chicago, Rock Island and Pacific Railroad Passenger Depot |
| Chicago, Rock Island and Pacific Railroad Passenger Station |
| Chicago, Rock Island & Pacific Railroad Depot |
| Chicago, Rock Island & Pacific Railroad Passenger Depot |
| Chickasaw County Courthouse |
| Chickasaw Octagon House |
| Christiansen, Jens Otto, House |
| Church of St. John the Baptist |
| Church of the Saviour Episcopal Church and David Henderson Statue |
| Church, Seymour, House |
| City Hall |
| City Hotel |
| City National Bank Building |
| Civic Center Historic District |
| Clarinda Carnegie Library |
| Clark-Blackwell House |
| Clarke, James F., House |
| Clark, Gerome, House |
| Clark House |
| Claussen, William, House |
| Clay County Courthouse |
| Clayton County Courthouse |
| Clayton School |
| Clemens Automobile Company Building |
| Clermont Public School |
| Clifton |
| Clinton County Courthouse |
| Clinton High School and Public Library |
Data from United States Park Service and Wikidata
