| Carter Jones Lumber | Stow | OH |
| Carthage Mills | Cincinnati | OH |
| Case Crane & Kilbourne Jacobs | Columbus | OH |
| Case Institute Library & Humaniti | Cleveland | OH |
| Case Institute Of Technology | Cleveland | OH |
| Case School Of Applied Science | Cleveland | OH |
| Case Western Reserve University | Cleveland | OH |
| Cash Sale | Cleveland | OH |
| Cashway Lumber | Ontario | OH |
| Cashway Lumber | Dover | OH |
| Cashway Lumber | Sandusky | OH |
| Cashway Lumber | Lewisville | OH |
| Cashway Lumber | Lisbon | OH |
| Cashway Lumber | Akron | OH |
| Cashway Lumber | Austinburg | OH |
| Cashway Lumber | Mogadore | OH |
| Cashway Lumber | Columbus Grove | OH |
| Cashway Lumber | Kent | OH |
| Castalia Cement | Castalia | OH |
| Castle Homes | Akron | OH |
| Castle Lumber | Canton | OH |
| Castruction | Boardman | OH |
| Castruction | Youngs | OH |
| Catalytic - PVC & Recovery Plant | Piqua | OH |
| Catawba Apartment | Worthington | OH |
| Caxton Building | Cleveland | OH |
| CDR Oscar | Cleveland | OH |
| Cecil Peck | Cleveland | OH |
| Cedar Apartments | Cleveland | OH |
| Cedar Locust | Canton | OH |
| Cedar Road Apartments | Cleveland | OH |
| Cedar School | Canton | OH |
| Cedarville Board Of Education | Cedarville | OH |
| Ceder Apartments | Cleveland | OH |
| CE Glass | Lancaster | OH |
| C.E.I. | Ashtabula | OH |
| CEI Power Plant | Cleveland | OH |
| Celina Stearic Acid | Celina | OH |
| Celluloid | Sandusky | OH |
| Celotex | Lockland | OH |
| Celotex | Cleveland | OH |
| Centerior Energy | Ashtabula | OH |
| Central Alloy Steel | Canton | OH |
| Central Aluminum | Columbus | OH |
| Central Avenue Shops | Toledo | OH |
| Central Branch | Dayton | OH |
| Central Brass | Cleveland | OH |
| Central Catholic High School | Canton | OH |
| Central Concrete Supply | Lima | OH |
| Central Foundry | Defiance | OH |
