Indiana - Criteria: C (architecture/engineering)
| Orange County Courthouse |
| Oriental Lodge No. 500 |
| Original Newburgh Historic District |
| Orleans Historic District |
| Orr Iron Company |
| Orr, Robert, Polygonal Barn |
| Orr, William, House |
| Osgood, Dr. H. G., House |
| Otis Park and Golf Course |
| Our Savior Lutheran Church |
| Owen County Courthouse |
| Oxford |
| Palace Lodge |
| Palace Theater |
| Palais Royale Building |
| Paoli Historic District |
| Paramount Theater Building |
| Parker, Oren F. and Adelia, House |
| Park Mary Historic District |
| Parkview Home of Clinton County |
| Patoka Bridges Historic District |
| Peabody Memorial Tower |
| Peacock Apartments |
| Pearl Steam Laundry |
| Pearson, Lora B., School |
| Pearson Terrace |
| Peirce, Oliver Webster Jr., and Catherine House |
| Pendleton Historic District |
| Pennslyvania Railroad Station |
| Pennsylvania |
| Perrin Historic District |
| Peru High School Historic District |
| Peters, Henry, House |
| Peters, John Claus, House |
| Phillips Bridge |
| Pierce, James, Jr., House |
| Pierceton Historic District |
| Pierson-Griffiths House |
| Pike County Courthouse |
| Pike Inn, Old |
| Pinehurst Hall |
| Pinhook Methodist Church and Cemetery |
| Place, Willard B., House |
| Plainfield Historic District |
| Plaza |
| Pleak, Strauther, Round Barn |
| Pleasant Hill Church |
| Pleasanton in Irvington Historic District |
| Plymouth Downtown Historic District |
| Plymouth Fire Station |
| Plymouth Northside Historic District |
| Plymouth Southside Historic District |
| Point Historic District |
| Pokagon State Park |
| Poland Presbyterian Church and Cemetery |
| Polk Street Concrete Cottage Historic District |
| Polk Street Terraces 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 |
| Portland Commercial Historic District |
| Portland Mills Bridge |
| Posey County Courthouse Square |
| Possom Bottom Covered Bridge |
| Potter's Covered Bridge |
| Potter, William, House |
| Pound, John, Store |
| Presbyterian Church Building |
| Princess Theatre |
| Proctor, William, House |
| Propylaeum, The (John W. Schmidt House) |
| Prospect Hill Historic District |
| Prosser House |
| Pugh Ford Bridge |
| Pulaski County Courthouse |
| Pullman-Standard Historic District |
| Purviance, David Alonzo and Elizabeth, House |
| Purviance, Samuel, House |
| Puster, L., and Company Furniture Manufactory |
| Puterbaugh, Joseph and Sarah, Farm |
| Putnam County Bridge No. 159 |
| Putnamville Presbyterian Church |
| Raber, Fred and Minnie, Farm |
| 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 |
| Rand, John Linsey, House |
| Randolph County Infirmary |
| Rangeline Road Bridge |
| Rank, Hugh and Leona, House |
| Rankin, Rebecca, Round Barn |
| Read Dunes House |
Data from United States Park Service and Wikidata
