Oo (25/25)

Oberhollabrunn, 1805	Ocean Pond	Oenophyta, 457 f.Kr.	Ohod, 625
Okinawa, 1945	Olmütz, 1758	Oltenita, 1853	Olustee, 1864
Omdurman, 1898	Oostende, 1601-04	Oporto, 1809	Oran I, 1509
Oran II, 1940	Orchard Knob-Indian Hill, 1863	Orchomenus, 85 f.Kr.	Oriskany, 1777
Orleans, 1428-29	Ostindien, 1941-42	Ostroleka, 1831	Oswego, 1756
Otterburn, 1388	Otumba, 1520	Oudenarde, 1708	Ourcq-floden, 1914
Ourique, 1139