| oberosterreich (Austria) |
Linz |
| Obwalden (Swiss canton) |
Sarnen |
| Offaly (Republic of Ireland) |
Tullamore |
| Ogooue-Ivindo (Gabon) |
Makokou |
| Ogoouó-Lolo (Gabon) |
Koulamoutou |
| Ogootre-Maritime (Gabon) |
Port-Gentil |
| Ogou (Togo) |
Atakpame |
| Ogun (Nigeria) |
Abeokuta |
| Ohangwena (Namibia) |
Oshikango |
| Ohio (USA) |
Columbus |
| Oio (Guinea-Bissau) |
Farim |
| Oise (France) |
Beauvais |
| Okavango (Namibia) |
Rundu |
| Okinawa (Japan) |
Naha City |
| Oklahoma (USA) |
Oklahoma City |
| Olancho (Honduras) |
Juticalpa |
| Olt (Romania) |
Slatina |
| Omaheke (Namibia) |
Gobabis |
| Oman |
Muscat |
| Ombella-Mpoko (CA Republic) |
Bimbo |
| Omniigovi (Mongolia) |
Dalandzadgad |
| Omusati (Namibia) |
Outapi |
| Ondo (Nigeria) |
Akure |
| Onotoa (Kiribati) |
Buariki |
| Ontario (Canada) |
Toronto |
| Oppland (Norway) |
Lillehammer |
| Orange Free State (South Africa) |
Bloemfontein |
| Oregon (USA) |
Salem |
| Orissa (India) |
Bhubaneswar |
| Orkney Islands |
Kirkwall |
| Orne (France) |
Alen |
| Oshana (Namibia) |
Oshakati |
| Oshikoto (Namibia) |
Tsumeb |
| Ossetia |
Vladikavkaz |
| Osterglitland (Sweden) |
Linkoping |
| Ostfold (Norway) |
Moss |
| Oti (Togo) |
Sansanne-Mango |
| Otjozondjupa (Namibia) |
Grootfontein |
| Ouaddai (Chad) |
Abeche |
| Ouaka (CA Republic) |
Bambari |
| Oubritenga (Burkina Faso) |
Ziniare |
| Oudalan (Burkina Faso) |
Gorom Gorom |
| Oudomxay (Laos) |
Xay |
| Oueme (Benin) |
Porto-Novo |
| Ouest (Cameroon) |
Bafoussam |
| Ouest (Haiti) |
Port-au-Prince |
| Ouham (CA Republic) |
Bossangoa |
| Ouham-Pende (CA Republic) |
Bozoum |
| Overijssel (Netherlands) |
Zwolle |
| Ovorhangay (Mongolia) |
Arvayheer |
| Oxfordshire (England) |
Oxford |
| Oyo (Nigeria) |
Ibadan |
