Ohio - Area of significance: Architecture
| Corning-White House |
| Corwin-Bolin House |
| Corwin Council House and Jail |
| Corwin House |
| Cory, Ambrose, House |
| Coshocton County Courthouse |
| Coshocton Main Street Historic District |
| Cote Bonneville |
| Cottage Hill Farm |
| Coulby, Harry, Mansion |
| Courthouse Center |
| Courtland Flats |
| Courtland, The |
| Court Street Firehouse |
| Covenant First Presbyterian Church |
| Cox, George B., House |
| Cox, Jacob D., House |
| Cozad, Justus L., House |
| Crabill, David, House |
| Crafts William H., House |
| Crandall Park-Fifth Avenue Historic District |
| Crane, Jonathan, Farm |
| Cranz, Edward, Farm |
| Cranz, William and Eugene, Farm |
| Crawfis Institute |
| Crawford-Tilden Apartments |
| Crescent, The |
| Crestline City Hall |
| Crist Tavern Annex-Millworkers Boarding House |
| Crittenden Farm |
| Croco House |
| Cronenwett, Georg, House |
| Crosley Building |
| Crossed Keys Tavern |
| Crumrine, John, Farm |
| Crumrine, Michael, Farm |
| Crystal Lake Stock Farm |
| Culbertson, Robert, House |
| Culbertson, William, House |
| Cummings, Wilson S., House |
| Cummins, David, Octagon House |
| Cummins School |
| Cunningham-Maier House |
| Curtiss, Marcus, Inn |
| Curtis, Walter, House |
| Curtis, William D., House |
| Cuvier Press Club |
| Cuyahoga Falls Downtown Historic District |
| Damascus Grade School |
| Damon, George, House |
| Dana, Marcus, House |
| Danford, Samuel, Farm, Church and Cemetery |
| Darke County Courthouse, Sheriff's House, And Jail |
| Datz, Walter, House |
| Davey, John, House |
| David's Reformed Church |
| Davis, Alexander, House |
| Davis and Dague Grocery Store, Old |
| Davis, Anson, House |
| Davis, Anson, Springhouse |
| Davis, James, Barn |
| Davis, James, Farm |
| Davis, Samuel Henry, House |
| Davis, Samuel, House |
| Dayton Arcade |
| Dayton Art Institute |
| Dayton-Campbell Historic District |
| Dayton Canoe Club |
| Dayton Country Club |
| Dayton Daily News Building |
| Dayton Fire Department Station No. 16 |
| Dayton Fire Station No. 14 |
| Dayton, James, House |
| Dayton, James, House, II |
| Dayton Motor Car Company Historic District |
| Dayton Power and Light Building Group |
| Dayton Stove and Cornice Works |
| Dayton Street Historic District |
| Dayton Terra-Cotta Historic District |
| Dayton View Historic District |
| Dayton View Triangle Historic District |
| Dayton Women's Club |
| Dayton Young Men's Christian Association Building |
| Dean Family Farm |
| Deardoff, Daniel L., House |
| Decker, Elias, Farmhouse |
| Decker, Henry, Farmstead |
| Decker, Stephen, Rowhouse |
| Deerlick Farm |
| Deersville Historic Distirct |
| Deerwood Farm |
| Defiance Downtown Historic District |
| Defiance Public Library |
| DeHeck, Albert, House |
| Deis, John, House |
| Deitz, Samuel, Farmhouse |
| Delashment, Elias, House |
| Delaware County Courthouse |
| Delaware County Jail and Sheriff's Residence |
| Delaware Post Office |
Data from United States Park Service and Wikidata
