Iowa - Role: Building
| Ranzow-Sander House |
| Raphael, Jacob, Building |
| Rath, Johann Christian Frederick, House |
| Rath Packing Company Administration Building |
| Ray, Frank G., House & Carriage House |
| Raymond, P. P., House |
| Reburn, Thomas, Polygonal Barn |
| Rector, Jason and Elizabeth Baylor, House |
| Red Ball Garage |
| Redfield GAR Hall |
| Red Oak Firehouse and City Jail |
| Red Oak Grove Presbyterian Church and Cemetery |
| Red Oak High School |
| Red Oak Public Library |
| Redstone |
| Reeve Electric Association Plant |
| 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, Anson O., House |
| Reynolds, Charles B., Round Barn |
| "Reynolds, Joseph ""Diamond Jo,"" Office Building and House" |
| Rhodes Mill |
| Richardson-Jakway House |
| Ricker, B. J., House |
| Rick's Brewery |
| Riekenberg, J. H., House |
| Riemenschneider, August and Josephine, Farmstead |
| Ringgold County Courthouse |
| Ringgold County Jail |
| Rittenmeyer, F. X., House |
| Robb House and Spring House |
| Roberts, Edward C., House |
| Roberts Octagon Barn |
| Robinson, George W. and Mary J. (Maxwell), House |
| Rock Crest-Rock Glen Historic District |
| Rockford Mill |
| Rock Island Passenger Depot |
| Rogers-Knutson House |
| Roling, Henry, House |
| Rollins, Ralph, House |
| Romey, George, House |
| Roosevelt Elementary School |
| Roosevelt School |
| Rose Hill |
| Rose Hill Methodist Episcopal Church |
| Roshek Brothers Department Store |
| Roslyn Flats |
| Round Barn, Bruce Township Section 3 |
| Round Barn, Buckingham Township |
| Round Barn, Cooper Township |
| Round Barn, Dubuque Township |
| Round Barn, Millville Township |
| Round Barn, Norway Township |
| Round Barn, Pilot Grove Township |
| Round Barn, Washington Township |
| Round Barn, Washington Township |
| Rowhouses at 702-712 Kirkwood Boulevard |
| Rownd, C. A., Round Barn |
| Ruan Center & Carriers Building |
| Rule, Duncan, House |
| Rumely-Des Moines Drug Company Building |
| Russell, Chuck and Emily, House |
| Russell, Rensselaer, House |
| Rye, Chris, House |
| Sac City Chicago and North Western Depot |
| Sac County Courthouse |
| Sacred Heart Catholic Church |
| Sacred Heart Hospital |
| Sacred Heart Roman Catholic Cathedral Complex |
| Sacred Heart School |
| Saengerfest Halle |
| Saint Ansgar Public School |
| Saint Barnabas Episcopal Church |
| Saint Boniface Church |
| Saint Irenaeus Church |
| Saint John's Roman Catholic Church |
| Saint Patrick's Catholic Church and Rectory |
| Saint Patrick's Roman Catholic Church |
| Saints Peter and Paul Catholic Church |
| Saints Peter and Paul Catholic Church |
| Saints Peter and Paul Church |
| Salisbury House |
| Sample, Hugh W. and Sarah, House |
| Sanborn, C. M., Building |
| Sandwich-Marseilles Manufacturing Building |
| Sanford, Arthur and Stella, House |
| Sankot Motor Company |
| Sargent's Garage |
| Sauser-Lane House |
| Savery Hotel |
| Schantz, Christian K. and Margaret (Rich), House and Carpentry Shop |
| Schebler, Richard, House |
Data from United States Park Service and Wikidata
