| Opernhaus Unter den Linden | Opernhaus Unter den Linden | Germany, Berlin | 1905-09-20 | -- | 1905 | 1 | |
| Öteki Tiyatro | Öteki Tiyatro | Turkey, Maltepe/ANKARA, Gazi Mustafa Kemal Bulvarı No:114-C | 2007-06-23 | -- | 2007 | 1 | |
| Open Space Theatre | Open Space Theatre | United States of America, New York | 1982-01-11 | -- | 1982 | 1 | |
| Obfelden | Obfelden | Switzerland | 2002-04-21 | -- | 2002 | 1 | |
| Oblastnoi dramteatr Volgograd | Oblastnoi dramteatr Volgograd | Russia, Volgograd | 1948-10- | -- | 1948 | 1 | |
| Ordway Center for the Performing Arts (Main Hall) | Ordway Center for the Performing Arts (Main Hall) | United States of America, Saint Paul, 345 Washington St | 2005-10-18 | 2005-10-19 | 2005 | 1 | |
| Opera House | Opera House | New Zealand, Wellington, 111/113 Manners Street | 1890-11-28 | 1890-11-29 | 1890 | 1 | |
| Obergrafschaft, Theater der | Theater der Obergrafschaft | Germany, Schüttorf, Hermann-Schlikker-Str. 1-3 | 2015-10-03 | -- | 2015 | 1 | |
| Orchard Theatre, the | The Orchard Theatre | England, Dartford, Home Gardens | 1996-03-12 | 1996-03-16 | 1996 | 1 | |
| Odda ungdomsskole | Odda ungdomsskole | Norway, Odda, Eidesmoen | 2006-11-15 | -- | 2006 | 1 | |
| Overholser Theatre | Overholser Theatre | United States of America, Ardmore | 1910-12-21 | 1910-12-21 | 1910 | 1 | |
| Opéra National de Lyon | Opéra National de Lyon | France, Lyon, 1 place de la Comédie | 2022-06-04 | 2022-06-13 | 2022 | 1 | |
| Old Rep at Birmingham Repertory Theatre | The Old Rep at Birmingham Repertory Theatre | England, Birmingham | 2013-03-14 | 2013-03-28 | 2013 | 1 | |
| Ophelia Theater | Ophelia Theater | United States of America, Astoria, 21-12 30th Road | 2016-10-28 | 2016-11-13 | 2016 | 1 | |
| Odorheiu Secuiesc | Odorheiu Secuiesc | Romania, Odorheiu Secuiesc | 1911-05-09 | -- | 1911 | 1 | |
| Ostróg | Ostróg | Poland, Ostróg | -- | -- | | | |
| Ornans | Ornans | France, Ornans | -- | -- | | | |
| Odessa | Одеса (Odessa) | Ukraine, Odessa | -- | -- | | | |
| Oituz | Oituz | Romania, Oituz | -- | -- | | | |
| Ornö | Ornö | Sweden, Ornö | -- | -- | | | |
| Ohgawara | Ohgawara | Japan, Ohgawara | -- | -- | | | |
| Osimo | Osimo | Italy | -- | -- | | | |
| Oppdal | Oppdal | Norway, Oppdal | -- | -- | | | |
| Opera House | Opera House | United States of America, Wyoming, Wyoming | -- | -- | | | |
| Obârşia | Obârşia | Romania, Obârşia | -- | -- | | | |
| Opole | Opole | Poland, Opole | -- | -- | | | |
| Olivenza | Olivenza | Spain, Olivenza | -- | -- | | | |
| Oddfellows' Hall | Oddfellows' Hall | Australia, Wagga Wagga, Fitzmaurice Street | -- | -- | | | |
| Oravice | Oravice | Slovak Republic, Oravice | -- | -- | | | |
| Oranienburg | Oranienburg | Germany, Oranienburg | -- | -- | | | |
| Opera House | Opera House | United States of America, Telluride | -- | -- | | | |
| Odder | Odder | Denmark, Odder | -- | -- | | | |
| Ogra | Ogra | Romania, Ogra | -- | -- | | | |
| Oulu | Oulu | Finland, Oulu | -- | -- | | | |
| Ocna Sibiului | Ocna Sibiului | Romania, Ocna Sibiului | -- | -- | | | |
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