Massachusetts - Area of significance: Community Planning
| North Cemetery |
| North Chester Historic District |
| North Easton Historic District |
| North Egremont Historic District |
| Northfield Center Cemetery |
| North High Street Historic District |
| North Leverett Historic District |
| North Lexington Street Historic District |
| North Rochester Congregational Church |
| Northside Historic District |
| North Street Fire Station |
| North Terminal Garage |
| North Town Hall |
| North Village Cemetery |
| North Worcester Aid Society |
| Norwood Memorial Municipal Building |
| Noves, Charles W., House |
| Nowland, J. Martin, House |
| Nye, Elnathan, House |
| Oakdale Village Historic District |
| Oak Grove Cemetery |
| Oak Grove Cemetery |
| Oak Grove Farm |
| Oak Knoll |
| O'Brien, Richard, Three-Decker |
| O'Connor, James-John Trybowski Three-Decker |
| O'Connor, James, Three-Decker |
| Ohabei Shalom Cemetery |
| Old Billerica Road Historic District |
| Old Burying Ground |
| Old Cemetery |
| Old Centre Historic District |
| Old Chestnut Hill Historic District |
| Old Colony Railroad Station |
| Old Douglas Center Historic District |
| Old Harbor Reservation Parkways, Metropolitan Park System of Greater Boston |
| Old Hose House |
| Old Lynn High School |
| Old Shipbuilder's Historic District |
| Old Stone Church |
| Old Town Center Historic District |
| Old Town Farm |
| Old Town Hall |
| Old Town Hall |
| Old Town Hall Historic District |
| Old Town Hall Historic District |
| Old Town Historic District |
| Old Village Historic District |
| Oliver House |
| Olmsted, Frederick Law, House, National Historic Site |
| Olmsted Park System |
| Olmsted Subdivision Historic District |
| Opposition House |
| Original Congregational Church of Wrentham |
| Orvis Road Historic District |
| Osterville Baptist Church |
| Otis Center Historic District |
| Otis Company Mill No. 1 |
| Otis-Wyman House |
| Our Lady Help of Christians Historic District |
| Outing Park Historic District |
| Oxford-Crown Extension District |
| Oxford Main Street Historic District |
| Oxford, The |
| Paine Estate |
| Paine Hollow Road South Historic District |
| Palmer Memorial Hall |
| Pan Burying Ground |
| Pan Historic District |
| Park Building |
| Parker-Burnett House |
| Parker, Capt. Nathaniel, Red House |
| Parker, Edmund, Jr., House |
| Parker, James, House |
| Parker, Joseph, House |
| Parkhill Mill |
| Park Street District |
| Park Street Firehouse |
| Peabody, George, House |
| Peabody Institute |
| Peabody, The |
| Peacock Farm Historic District |
| Pearl Street School |
| Peck, John M., House |
| Peirce, Edward, House-Henderson House of Northeastern University |
| Pembroke Friends Meetinghouse |
| Pepperell Center Historic District |
| Perry Avenue Historic District |
| Petersham Common Historic District |
| Petterson, Lars-Adolph Carlson Three-Decker |
| Petterson, Lars-Fred Gurney Three-Decker |
| Petterson,Lars-James Reidy Three-Decker |
| Petterson, Lars-Silas Archer Three-Decker |
| Phillipston Center Historic District |
| Pierce, F. Lincoln, Houses |
| Piety Corner Historic District |
| Pilgrim Congregational Church |
| Pilgrim Congregational Church |
| Pill Hill Historic District |
| Pine Grove Cemetery |
Data from United States Park Service and Wikidata
