Ohio - Area of significance: Architecture
| Procter and Collier-Beau Brummell Building |
| Promont |
| Prospect Avenue Row House Group |
| Prospect Hill Historic District |
| Prospect Place |
| Pugh-Kittle House |
| Purcell, Robert A. and Elizabeth H., House |
| Purdum-Tracy House |
| Putman, Walter S., House |
| Putnam County Courthouse |
| Putnam Historic District |
| Putnam, Rufus, House |
| Pythian Castle |
| Pythian Temple and James Pythian Theater |
| Quad Hall |
| Race Street Historic District |
| Rae, Capt., House |
| Raemelton Farm Historic District |
| Rager, John, Farmhouse |
| Ragersville School |
| Randall, Dr. Rufus, Residence |
| Rankin Building |
| Rankin Historic District |
| Ranney, Luther B., Farm |
| Ransley Apartment Building |
| Ratterman, Bernard, House |
| Rattermann, Heinrich A., House |
| Rauh, Frederick and Harriet, House |
| Rawlings-Brownell House |
| Rawson House |
| Rayen School |
| Raymond, Frank Mason, House |
| Raymond, Liberty G., Tavern and Barn |
| Reakirt Building |
| Realty Building |
| Reamer Barn |
| Reaves, John, House |
| Reber, Valentine, House |
| Red Brick Tavern |
| Redington Block |
| Redlands |
| Red Oak Presbyterian Church |
| Red Oak-Sherman, William C., House |
| Reed, C. A., House |
| Reed, Henry, Jr., House |
| Reed, James, House |
| Reed, Joseph G., Company |
| Reefy, Frederick, House |
| Reeves, Jeremiah, House and Carriage House |
| Regal Theater |
| Reid, Whitelaw, House |
| Reily, Robert, House |
| Renick Farm |
| Renick House, Paint Hill |
| Renkert, Harry S., House |
| Renner, George J., Jr., House |
| Rentschler House |
| Renz Block |
| Republic Iron and Steel Office Building |
| Resor, William, House |
| Retszch, W. C., House |
| Reynolds, John R., House |
| Rhoads, Peter F., House |
| Rhodes and Watters Apartment Buildings, The |
| Rial, York, House |
| Richard, John, Residence |
| Rich, Charles B., House |
| Richey, James, Farmhouse |
| Richland County Infirmary |
| Richland Trust Building |
| Richman Brothers Company, The |
| Riddle Block |
| Riddle Block #11 |
| Riddle Block #9 |
| Riddle-Friend House |
| Rider, Adam, House |
| Ridgewood Historic District |
| Riley, Calvin E., House |
| Riley, F., House |
| Rinderknecht, Christian H., House |
| Rinehart, Hugh T., House |
| Rings, Louis, Residence |
| Ring, Walter, House and Mill Site |
| Ripley Historic District |
| Ripley House |
| Risingsun Town Hall and Opera House |
| Ritter, William, House |
| Riverside Cemetery Building |
| Riverside Cemetery Chapel |
| Riverside Chapel |
| Riverview |
| Riverview Apartments |
| Riverview House Apartments |
| Roach, Moses and Minerva, House |
| Roas-Ilhardt Farm and Winery |
| Robb, L. B., Drugstore |
| Robeson, Dr. Donovan, House |
| Robinson Building |
| Robinson, Byron W., House |
| Robinson, Edmund, House |
Data from United States Park Service and Wikidata
