All - Architectural style - Greek Revival architecture
| Nishnabotna Ferry House |
| Niskayuna Reformed Church |
| Nitschke, Oswald J., House |
| Noank Historic District |
| Noble, Alexander, House |
| Noble Hall |
| Nooney, William , House |
| Norfield Historic District |
| Norfolk County Courthouse |
| Norman, Felix Grundy, House |
| Norridgewock Female Academy |
| Northampton County Courthouse Square |
| North Avenue Congregational Church |
| North Bend |
| North East Historic District |
| Northern Bank of Kentucky |
| Northern Methodist Episcopal Church of Clarksville |
| North Fork Valley Rural Historic District |
| North Hall, University of Wisconsin |
| North Hillsdale Methodist Church |
| North Main Street Historic District |
| North Milford Historic District |
| North Ridge United Methodist Church |
| Northrop, Julia Carter, House |
| Northrup-Gilbert House |
| North Salina Street Historic District |
| North School |
| Northside Historic District |
| Northside United Presbyterian |
| North Star School District No. 11 |
| North Street Friends Meetinghouse |
| North Town Hall |
| Northwest Marietta Historic District |
| North Wheeling Historic District |
| North Wilmot Union Meetinghouse |
| Northwood Congregational Church |
| North Yarmouth Academy |
| Notre Dame Academy and Notre Dame High School |
| Nottoway Plantation House |
| Nowland House |
| Noxon Bank Building |
| Noyes, John, House |
| Nuckolls-Jefferies House |
| Nut Grove |
| Nutwood |
| Oak Alley Plantation |
| Oakcliff |
| Oakforest |
| Oak Grove |
| Oak Grove |
| Oak Grove |
| Oak Hill |
| Oak Hill |
| Oak Hill Methodist Episcopal Church |
| Oak Hill Park Historic District |
| Oak Hill Welsh Congregational Church |
| Oakhurst |
| Oakland |
| Oakland |
| Oakland Chapel |
| Oakland Hall |
| Oak Lawn |
| Oaklawn Farm |
| Oakleigh |
| Oakleigh Garden Historic District (Boundary Decrease & Additional Documentation) |
| Oakley Farm |
| Oakley Hill |
| Oakmont |
| Oak Plain Presbyterian Church |
| Oak Ridge |
| Oakslea Place |
| Oaks, The |
| Oaks, The |
| Oak Top |
| Oakwood |
| Oakwood |
| Oakwood Cemetery |
| O'Brien-Peuschel Farmstead |
| Ocean County Courthouse |
| Octorara Farm |
| Odd Fellows Hall |
| Odd Fellows Hall |
| Odd Fellows Lodge |
| Oden, Dr. Hezekiah, House |
| Offerman, John, House |
| Office and Banking House of West Feliciana Railroad |
| Ogburn, Henry, House |
| Oglebay Mansion Museum |
| Ohio Statehouse |
| Ohio Street Methodist Episcopal Church Complex |
| Okauchee House |
| Old Bartlett and Goble Store |
| Old Bergen Church |
| Old Bethel United Methodist Church |
| Old Bnai Zion Synagogue |
| Old Cape May County Courthouse Building |
| Old Capitol |
| Old Cathedral Complex |
| Old Centre, Centre College |
| Old Cokesbury and Masonic Female College and Conference School |
Data from United States Park Service and Wikidata
