Indiana - Role: Building
| O'Brien Electric Priming Company |
| O'Donnell Building |
| O'Hair, James Edington Montgomery, House |
| Old Bittermann Building |
| Old Cathedral Complex |
| Old Clarksville Site |
| Old Clifty Church |
| Old Courthouse (Second St. Joseph County Courthouse) |
| Old Crescent, The |
| Olde Store (John O'Ferrell Store) |
| Old Fellwock Auto Company |
| Oldfields |
| Old Frankfort Stone High School |
| Old Hoosier Theatre |
| Old Newburgh Presbyterian Church |
| Old Pathology Building |
| Old Perry County Courthouse |
| Old State Bank |
| Old Timbers |
| Old Vanderburgh County Courthouse |
| Old Warrick County Jail |
| Oliver, Joseph D., House |
| O'Neall, Abijah II, House |
| Opel, John, House |
| Orange County Courthouse |
| Oriental Lodge No. 500 |
| Orr Iron Company |
| Orr, Robert, Polygonal Barn |
| Orr, William, House |
| Osgood, Dr. H. G., House |
| Our Savior Lutheran Church |
| Owen County Courthouse |
| Oxford |
| Oxford Community Mausoleum |
| Oxford Hotel |
| Palace Lodge |
| Palace Theater |
| Palais Royale Building |
| Paramount Theater Building |
| Parker, Oren F. and Adelia, House |
| Parkview Home of Clinton County |
| Parson and Scoville Building |
| Patoka Church of God in Christ-Patoka Colored School |
| Patterson, J.W., House |
| Peacock Apartments |
| Pearl Steam Laundry |
| Pearson, Lora B., School |
| Pearson Terrace |
| Peirce, Oliver Webster Jr., and Catherine House |
| Pennslyvania Railroad Station |
| Pennsylvania |
| Pennsylvania Railroad Station |
| Peters, Henry, House |
| Peters, John Claus, House |
| Pierce, James, Jr., House |
| Pierson-Griffiths House |
| Pike County Courthouse |
| Pike Inn, Old |
| Pinehurst Hall |
| Pinhook Methodist Church and Cemetery |
| Place, Willard B., House |
| Plaza |
| Pleak, Strauther, Round Barn |
| Pleasant Hill Church |
| Pleasant Lake Depot |
| Pletcher, Richard and Susan, House |
| Plymouth Fire Station |
| Poland Presbyterian Church and Cemetery |
| Polk Street Concrete Cottage Historic District |
| Polk Township District No. 2 School |
| Pollard-Nelson House |
| Porter County Jail and Sheriff's House |
| Porter County Memorial Hall |
| Porter, Gene Stratton, Cabin |
| Porter, Gene Stratton, Cabin |
| Porter Pool Bathhouse |
| Porter Town Hall |
| Posey County Courthouse Square |
| Potter, William, House |
| Pound, John, Store |
| Presbyterian Church Building |
| Prill School |
| Princess Theatre |
| Proctor, William, House |
| Propylaeum, The (John W. Schmidt House) |
| Prosser House |
| Pryor's Country Place |
| Pulaski County Courthouse |
| Pulaski County Home |
| Purviance, David Alonzo and Elizabeth, House |
| Purviance, Samuel, House |
| Puster, L., and Company Furniture Manufactory |
| Puterbaugh, Joseph and Sarah, Farm |
| Putnamville Presbyterian Church |
| Ragsdale, William A., House |
| Rakestraw House |
| Ralph Waldo Emerson Indianapolis Public School #58 |
| Ramsay-Fox Round Barn and Farm |
| Ranck, Thomas, Round Barn |
| Randall Building |
Data from United States Park Service and Wikidata
