Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Notre Dame Academy | School | 12 | District of Columbia | 38 54 07 N | 077 00 36 W |
| Notre Dame Convent | Building | 10 | District of Columbia | 38 54 08 N | 077 00 31 W |
| Noyes Armillary Sphere | Park | 41 | District of Columbia | 38 55 09 N | 077 02 08 W |
| Noyes Elementary School | School | 46 | District of Columbia | 38 55 29 N | 076 59 30 W |
| Noyes Playground | Park | 46 | District of Columbia | 38 55 29 N | 076 59 30 W |
| Noyes Recreation Center | Park | 47 | District of Columbia | 38 55 30 N | 076 59 29 W |
| Nugent Hall | Building | 67 | District of Columbia | 38 56 15 N | 077 00 07 W |
| Nursing-Biology Building | Building | 51 | District of Columbia | 38 56 02 N | 076 59 47 W |
| O Street Market | Locale | 28 | District of Columbia | 38 54 31 N | 077 01 24 W |
| O'Boyle Hall | Building | 80 | District of Columbia | 38 56 18 N | 077 00 06 W |
| O'Briens Court (historical) | Locale | 9 | District of Columbia | 38 53 41 N | 077 02 32 W |
| O'Donovan Dining Hall | Building | | District of Columbia | 38 54 21 N | 077 04 32 W |
| Oak Grove Post Office (historical) | Post Office | 107 | District of Columbia | 38 59 03 N | 077 01 36 W |
| Oak Hill (historical) | Building | 72 | District of Columbia | 38 55 47 N | 077 03 22 W |
| Oak Hill Cemetery | Cemetery | 29 | District of Columbia | 38 54 46 N | 077 03 23 W |
| Oak Hill Cemetery Chapel | Church | 46 | District of Columbia | 38 54 47 N | 077 03 32 W |
| Oak Hill Cemetery Gatehouse | Building | 44 | District of Columbia | 38 54 47 N | 077 03 32 W |
| Obelisk Gallery (historical) | Building | 29 | District of Columbia | 38 54 31 N | 077 03 54 W |
| Oblate College (historical) | School | 60 | District of Columbia | 38 55 49 N | 077 00 06 W |
| Observatory Circle | Locale | 69 | District of Columbia | 38 55 26 N | 077 03 54 W |
| Octagon House | Building | 15 | District of Columbia | 38 53 47 N | 077 02 29 W |
| Octagonal House (historical) | Building | 51 | District of Columbia | 38 54 55 N | 077 02 55 W |
| Odd Fellows Hall (historical) | Building | 10 | District of Columbia | 38 53 43 N | 077 01 19 W |
| Odeon Theatre (historical) | Building | 5 | District of Columbia | 38 53 33 N | 077 01 08 W |
| Office of Personnel Management Building | Building | 11 | District of Columbia | 38 53 42 N | 077 02 39 W |
| Office of the U S Trade Representative | Building | 15 | District of Columbia | 38 53 51 N | 077 02 23 W |
| Old Adas Israel Synagogue (historical) | Church | 12 | District of Columbia | 38 53 54 N | 077 01 12 W |
| Old Brick Capitol (historical) | Building | 27 | District of Columbia | 38 53 25 N | 077 00 16 W |
| Old British Legation Building (historical) | Building | 23 | District of Columbia | 38 54 26 N | 077 02 32 W |
| Old Capitol Prison (historical) | Building | 27 | District of Columbia | 38 53 25 N | 077 00 16 W |
| Old City Hall | Building | 16 | District of Columbia | 38 53 43 N | 077 01 04 W |
| Old Cosmos Club (historical) | Building | 18 | District of Columbia | 38 53 58 N | 077 02 05 W |
| Old Engine Company Number 6 | Building | 14 | District of Columbia | 38 54 01 N | 077 00 60 W |
| Old Executive Office Building | Building | 14 | District of Columbia | 38 53 50 N | 077 02 19 W |
| Old Fenwick Homestead (historical) | Locale | 63 | District of Columbia | 38 59 09 N | 077 02 23 W |
| Old French Embassy | Building | 55 | District of Columbia | 38 55 21 N | 077 02 11 W |
| Old General Post Office | Post Office | 110 | District of Columbia | 38 58 04 N | 077 04 34 W |
| Old Holy Trinity Church | Church | 34 | District of Columbia | 38 54 24 N | 077 04 10 W |
| Old Main (historical) | Building | 42 | District of Columbia | 38 55 20 N | 077 01 20 W |
| Old Main Building | Building | 12 | District of Columbia | 38 53 54 N | 077 01 41 W |
| Old Masonic Hall | Building | 11 | District of Columbia | 38 53 50 N | 077 01 27 W |
| Old Methodist Burying Ground (historical) | Cemetery | 27 | District of Columbia | 38 54 37 N | 077 03 17 W |
| Old National Museum (historical) | Building | 9 | District of Columbia | 38 53 11 N | 077 01 28 W |
| Old National Race Course (historical) | Locale | 52 | District of Columbia | 38 50 40 N | 076 59 49 W |
| Old Naval Hospital | Hospital | 23 | District of Columbia | 38 52 59 N | 076 59 34 W |
| Old Naval Observatory | Locale | 28 | District of Columbia | 38 53 43 N | 077 03 07 W |
| Old North Building | Building | 45 | District of Columbia | 38 54 27 N | 077 04 23 W |
| Old Post Office Pavilion and Tower | Building | 4 | District of Columbia | 38 53 38 N | 077 01 41 W |
| Old Providence Hospital (historical) | Hospital | | District of Columbia | 38 53 04 N | 077 00 12 W |
| Old Providence Market (historical) | Building | 21 | District of Columbia | 38 53 04 N | 077 00 11 W |
| Old South Building (historical) | Building | 44 | District of Columbia | 38 54 26 N | 077 04 26 W |
| Old Stone House | Building | 17 | District of Columbia | 38 54 19 N | 077 03 37 W |
| Old Toll Gate Site (historical) | Building | 27 | District of Columbia | 38 54 02 N | 076 58 26 W |
| Old Vat (historical) | Building | 5 | District of Columbia | 38 53 44 N | 077 03 19 W |
| Old Way Baptist Church | Church | 14 | District of Columbia | 38 54 00 N | 076 59 09 W |
| Olive Grove Baptist Church | Church | 13 | District of Columbia | 38 52 10 N | 076 58 44 W |
| Olive Risely Seward Statue | Park | 25 | District of Columbia | 38 53 11 N | 076 59 52 W |
| On Leong Chinese Merchants Association Building | Building | 14 | District of Columbia | 38 53 58 N | 077 01 16 W |
| Open Door Baptist Church | Church | 39 | District of Columbia | 38 53 11 N | 076 55 14 W |
| Orbit Sculpture | Park | 84 | District of Columbia | 38 55 43 N | 077 03 43 W |
| Orchard Hill | Building | 110 | District of Columbia | 38 55 58 N | 077 04 59 W |
| Orchard Hill (historical) | Building | 110 | District of Columbia | 38 56 00 N | 077 04 59 W |
| Organization of American States Annex | Building | 6 | District of Columbia | 38 53 33 N | 077 02 34 W |
| Organization of American States Building | Building | 5 | District of Columbia | 38 53 33 N | 077 02 24 W |
| Original Patentees of District of Columbia Memorial | Park | 4 | District of Columbia | 38 53 38 N | 077 02 01 W |
| Ormes Luck (historical) | Civil | 16 | District of Columbia | 38 54 22 N | 077 03 14 W |
| Orr Elementary School | School | 10 | District of Columbia | 38 52 21 N | 076 58 27 W |
| Orr Recreation Center | Park | 8 | District of Columbia | 38 52 20 N | 076 58 31 W |
| Osborn Building | Building | 105 | District of Columbia | 38 56 15 N | 077 05 29 W |
| Oscar S Straus Memorial Fountain | Park | 4 | District of Columbia | 38 53 38 N | 077 01 55 W |
| Oscar W Underwood House | Building | 19 | District of Columbia | 38 53 54 N | 077 02 43 W |
| Oswego and Exeter Apartments | Building | 31 | District of Columbia | 38 55 00 N | 077 01 50 W |
| Our Lady of Perpetual Help Catholic Church | Church | 82 | District of Columbia | 38 51 27 N | 076 58 56 W |
| Our Lady of Perpetual Help School | School | 80 | District of Columbia | 38 51 27 N | 076 58 53 W |
| Our Lady of Victory Roman Catholic Church | Church | 17 | District of Columbia | 38 54 38 N | 077 05 42 W |
| Our Lady Queen of Peace School | School | 53 | District of Columbia | 38 53 00 N | 076 56 51 W |
| Our Lady Queen of the Americas Roman Catholic Church | Church | 50 | District of Columbia | 38 54 56 N | 077 02 57 W |
| Our Redeemer Lutheran Church | Church | 33 | District of Columbia | 38 55 13 N | 077 01 23 W |
| Outlet Bridge | Bridge | 1 | District of Columbia | 38 52 57 N | 077 01 59 W |
| Outlet Gates | Building | 1 | District of Columbia | 38 52 57 N | 077 01 59 W |
| Oxon Creek | Bay | 1 | District of Columbia | 38 48 26 N | 077 01 35 W |
| Oxon Run | Stream | | District of Columbia | 38 49 01 N | 077 00 23 W |
| Oxon Run Parkway | Park | 23 | District of Columbia | 38 50 20 N | 076 59 09 W |
| Oyster Elementary School | School | | District of Columbia | 38 55 24 N | 077 03 24 W |
| P Street Bridge | Bridge | 5 | District of Columbia | 38 54 35 N | 077 03 00 W |
| Pablo Benito Juarez Memorial | Park | 11 | District of Columbia | 38 53 56 N | 077 03 13 W |
| Palais Royale Building (historical) | Building | 13 | District of Columbia | 38 53 54 N | 077 01 37 W |
| Palisades Branch Library | Building | 52 | District of Columbia | 38 55 06 N | 077 05 50 W |
| Palisades Dairy Farm (historical) | Locale | 80 | District of Columbia | 38 55 05 N | 077 05 24 W |
| Palisades Park | Park | 70 | District of Columbia | 38 55 33 N | 077 05 44 W |
| Palisades Playground | Park | 43 | District of Columbia | 38 55 29 N | 077 06 17 W |
| Palisades Post Office | Post Office | 44 | District of Columbia | 38 55 33 N | 077 06 11 W |
| Palisades Recreation Center | Park | 42 | District of Columbia | 38 55 30 N | 077 06 19 W |
| Palmer House (historical) | Building | 19 | District of Columbia | 38 54 04 N | 077 01 59 W |
| Pan American Health Organization | Building | 18 | District of Columbia | 38 53 46 N | 077 02 59 W |
| Pan American Union | Building | 6 | District of Columbia | 38 53 34 N | 077 02 25 W |
| Panama Legation Building | Building | 26 | District of Columbia | 38 54 38 N | 077 02 31 W |
| Pangborn Hall | Building | 51 | District of Columbia | 38 56 03 N | 076 59 48 W |
| Parish House | Building | 19 | District of Columbia | 38 54 01 N | 077 02 08 W |
| Park Place | Populated Place | 58 | District of Columbia | 38 55 50 N | 077 00 19 W |
| Park Tower | Building | 54 | District of Columbia | 38 55 18 N | 077 02 11 W |
| Park View | Populated Place | 59 | District of Columbia | 38 55 55 N | 077 01 25 W |
| Park View Elementary School | School | 67 | District of Columbia | 38 56 04 N | 077 01 17 W |
| Parkington | Building | 27 | District of Columbia | 38 53 28 N | 077 00 19 W |
| Parklands-Turner Community Library | Building | 58 | District of Columbia | 38 50 47 N | 076 58 53 W |
| Parkside Playground | Park | 5 | District of Columbia | 38 54 00 N | 076 57 19 W |
| Parkview Playground | Park | 66 | District of Columbia | 38 56 06 N | 077 01 18 W |
| Parkview Recreation Center | Park | 66 | District of Columbia | 38 56 06 N | 077 01 17 W |
| Parrotts Woods | Woods | 29 | District of Columbia | 38 54 46 N | 077 03 23 W |
| Pasquerilla Healthcare Center | Building | | District of Columbia | 38 54 38 N | 077 04 31 W |