Maryland - Criteria: C (architecture/engineering)
| Public Safety Building |
| Public School No. 109 |
| Public School No. 111 |
| Public School No. 25 |
| Public School No. 37 |
| Public School No. 99 |
| Purnell, George Washington, House |
| Quarter Place |
| Queenstown Rosenwald School |
| Queponco Railway Station |
| Quindocqua United Methodist Church |
| Radnor-Winston Historic District |
| Ravenshurst |
| Readbourne |
| Reed's Creek Farm |
| Rehobeth Presbyterian Church |
| Rehoboth |
| Reisterstown Historic District |
| Reservoir Hill Historic District |
| Retreat |
| Reward |
| Reward-Tilden's Farm |
| Richards, Thomas, House |
| Rich Hill |
| Rich Hill |
| Richland |
| Richland Farm |
| Rich Mountain |
| Ridgeley School |
| Ridgely's Delight Historic District |
| Ridge, The |
| Ridgeton Farm |
| Ridgley Methodist Episcopal Church |
| Rieman Block |
| Rigbie House |
| Riley-Bolten House |
| Rising Sun Inn |
| Riverdale Park Historic District |
| Riversdale |
| Riverside Historic District |
| River View, The |
| Riviera Apartments |
| Roberts Inn |
| Robinson House |
| Rock Clift |
| Rock Creek Methodist Episcopal Church |
| Rock Creek Woods Historic District |
| Rockdale |
| Rockland |
| Rockland Farm |
| Rockland Farm |
| Rockland Historic District |
| Rockledge |
| Rock Methodist Episcopal Church |
| Rock United Presbyterian Church |
| Rockville Park Historic District |
| Rockville Railroad Station |
| Roddy Road Covered Bridge |
| Rodgers Forge Historic District |
| Rodgers Tavern |
| Rohrer House |
| Roland Park Historic District |
| Rolling Mill Historic District |
| Rombro Building |
| Roop's Mill |
| Rosehill |
| Rose Hill |
| Rose Hill |
| Rose Hill |
| Rose Hill |
| Rose Hill Manor |
| Rosemary Lawn |
| Round About Hills |
| Routzahn-Miller Farmstead |
| ROVER (log canoe) |
| Rowhouses at 303-327 East North Avenue |
| Royer, Christian, House |
| Rudisel, Ludwick, Tannery House |
| Ruscombe |
| Saint Mary's Rectory |
| Saint Michaels Mill |
| Saleaudo |
| Salisbury Plantation |
| Salmon-Stohlman House |
| Samester Parkway Apartments |
| Sandgates On Cat Creek |
| San Domingo School |
| SANDY (log canoe) |
| Sandy Point Farmhouse |
| Sandy Point Shoal Light Station |
| Sandy Spring Friends Meetinghouse |
| Sanitary Laundry Company Building |
| Sarum |
| S. C. DOBSON (log canoe) |
| Scheifferstadt |
| Schoolhouse, Denton |
| School No. 27 (Commodore John Rodgers Elementary School) |
| Schoolridge Farm |
| Schuler, Hans, Studio and Residence |
| Schwartze Mansion |
Data from United States Park Service and Wikidata
