Iowa - Area of significance: Architecture
| Plymouth Place |
| Pocahontas County Courthouse |
| Podhajsky-Jansa Farmstead District |
| Pohlmann, Elizabeth, House |
| Pohlmann, Henry, House |
| Poldberg, Chris, Farmstead |
| Polk County Courthouse |
| Polk County Homestead and Trust Company Addition Historic District |
| Poplar Rural District |
| Porter Hall |
| Porter-Rhynsburger House |
| Pottawattamie County Jail |
| Pottawattamie County Sub Courthouse |
| Potter's, E. G., Jasper Flour Mill |
| Potter-Williams House |
| Poweshiek County Courthouse |
| Prairie Grove School |
| Pratt, A. W., House |
| Price, Hiram/Henry Vollmer House |
| Price, Rialto, House |
| Prien Building |
| Priester Building, The |
| Primrose Mill |
| Princess-Sweet Shop |
| Prospect Park Historic District |
| Prospect Park Second Plat Historic District |
| Public Library of Des Moines |
| Public Square Historic District |
| Pucker Street Historic District |
| Purdy, Eliphalet W. and Catherine E. Jaquish, House |
| Putnam-Parker Block |
| Pyle, Glenn O. and Lucy O., House |
| Quasdorf Blacksmith and Wagon Shop |
| Queen, Hogan and Martha A. Runkle, House |
| Quickel, Jacob, House |
| Radcliff, Willam, House |
| Raible, F. J., House |
| Ranshaw, Samuel and Emma A., House |
| Ranzow-Sander House |
| Raphael, Jacob, Building |
| Rath, Johann Christian Frederick, House |
| Ray, Frank G., House & Carriage House |
| Raymond, P. P., House |
| Rector, Jason and Elizabeth Baylor, House |
| Red Ball Garage |
| Redmond Park-Grande Avenue Historic District |
| Red Oak Grove Presbyterian Church and Cemetery |
| Red Oak Public Library |
| Redstone |
| Reeve, Leander, House |
| Reeves, Isaac and Agnes (Bells), House |
| Regina Coeli Monastery |
| Register and Tribune Building |
| Reichert, John Christian and Bertha Landrock, House |
| Renken, Renke and Wubke, House |
| Renwick Building |
| Renwick House |
| Reverend Little's Young Ladies Seminary |
| Rewerts, George, House |
| Reynolds, Charles B., Round Barn |
| Richardson-Jakway House |
| Ricker, B. J., House |
| Riekenberg, J. H., House |
| Riemenschneider, August and Josephine, Farmstead |
| Ringgold County Courthouse |
| Ringgold County Jail |
| Rittenmeyer, F. X., House |
| Riverview Park Plat Historic District |
| Riverview Terrace Historic District |
| Robb House and Spring House |
| Roberts, Edward C., House |
| Robinson, George W. and Mary J. (Maxwell), House |
| Rock Crest-Rock Glen Historic District |
| Rockford Mill |
| Rock Island Passenger Depot |
| Rogers, George W. Company Shot Tower |
| Roling, Henry, House |
| Rollins, Ralph, House |
| Romey, George, House |
| Roosevelt Elementary School |
| Roosevelt School |
| Rose Hill |
| Rose Hill Historic District |
| Rose Hill Methodist Episcopal Church |
| Roshek Brothers Department Store |
| Roslyn Flats |
| Ross Grain Elevator |
| Rowhouses at 702-712 Kirkwood Boulevard |
| Royal Neighbors of America National Home Historic District |
| Ruan Center & Carriers Building |
| Rule, Duncan, House |
| Russell, Chuck and Emily, House |
| Russell, Rensselaer, House |
| Rye, Chris, House |
| Sac City Chicago and North Western Depot |
| Sac City Monument Square Historic District |
| Sac County Courthouse |
| Sacred Heart Catholic Church |
| Sacred Heart Hospital |
| Sacred Heart Roman Catholic Cathedral Complex |
Data from United States Park Service and Wikidata
