| Obo |
Haut-Mbomou (CA Republic) |
| Oddur (Xuddur) |
Bakool (Somalia) |
| Odense |
Fyn (Denmark) |
| Ohonua |
Eua (Tonga) |
| Oklahoma City |
Oklahoma (USA) |
| Olaki |
Arua (Uganda) |
| Olympia |
Washington (USA) |
| Omagh |
Tyrone (Northern Ireland) |
| Ondorhaan |
Hentiy (Mongolia) |
| Onverwacht |
Para (Suriname) |
| Opuwo |
Kunene (Namibia) |
| Oradea |
Bihor (Romania) |
| Oranjestad |
Aruba |
| Oranjestad |
St Eustatius (Netherland Antilles) |
| Orleans |
Loiret (France) |
| Orodara |
Kenedougou (Burkina Faso) |
| Oshakati |
Oshana (Namibia) |
| Oshikango |
Ohangwena (Namibia) |
| Oslo |
Norway |
| Ostersund |
Jamtland (Sweden) |
| Otsu |
Shiga (Japan) |
| Ottawa |
Canada |
| Ouagadougou |
Burkina Faso |
| Ouagadougou |
Kadiogo (Burkina Faso) |
| Ouahigouya |
Yatenga (Burkina Faso) |
| Ouesso |
Sangha (Congo) |
| Outapi |
Omusati (Namibia) |
| Oviedo |
Asturias (Spain) |
| Owando |
Guyette (Congo) |
| Owerri |
Imo (Nigeria) |
| Oxford |
Oxfordshire (England) |
| Oyem |
Woleu-Ntem (Gabon) |
