| Oituz | Oituz | Romania, Oituz | -- | -- | | | |
| Ohgawara | Ohgawara | Japan, Ohgawara | -- | -- | | | |
| Osimo | Osimo | Italy | -- | -- | | | |
| Oppdal | Oppdal | Norway, Oppdal | -- | -- | | | |
| Opole | Opole | Poland, Opole | -- | -- | | | |
| Olivenza | Olivenza | Spain, Olivenza | -- | -- | | | |
| Oddfellows' Hall | Oddfellows' Hall | Australia, Wagga Wagga, Fitzmaurice Street | -- | -- | | | |
| Obârşia | Obârşia | Romania, Obârşia | -- | -- | | | |
| Oravice | Oravice | Slovak Republic, Oravice | -- | -- | | | |
| Opera House | Opera House | United States of America, Telluride | -- | -- | | | |
| Oranienburg | Oranienburg | Germany, Oranienburg | -- | -- | | | |
| Odder | Odder | Denmark, Odder | -- | -- | | | |
| Oulu | Oulu | Finland, Oulu | -- | -- | | | |
| Ogra | Ogra | Romania, Ogra | -- | -- | | | |
| Ostróg | Ostróg | Poland, Ostróg | -- | -- | | | |
| Opera House | Opera House | United States of America, Wyoming, Wyoming | -- | -- | | | |
| Ocna Sibiului | Ocna Sibiului | Romania, Ocna Sibiului | -- | -- | | | |
| Ornans | Ornans | France, Ornans | -- | -- | | | |
| Odessa | Одеса (Odessa) | Ukraine, Odessa | -- | -- | | | |
| Ornö | Ornö | Sweden, Ornö | -- | -- | | | |
| Opera House | Opera House | United States of America, Pensacola | 1903-10-25 | 1903-10-25 | 1903 | 1 | |
| Oravais Teater | Oravais Teater | Finland, Kimo, Oravais, Kyroboas Kvarn | 1996-07-11 | -- | 1996 | 1 | |
| Ontmoetingscentrum d'Iefte | Ontmoetingscentrum d'Iefte | Belgium, Deerlijk, Hoogstraat 122 | 2002-01-14 | 2002-01-15 | 2002 | 1 | |
| Olofström | Olofström | Sweden, Olofström | 1992-11-12 | -- | 1992 | 1 | |
| Oblastnoi dramteatr Volgograd | Oblastnoi dramteatr Volgograd | Russia, Volgograd | 1948-10- | -- | 1948 | 1 | |
| Old Town Players | Old Town Players | United States of America, Chicago | 1973-02-09 | 1973-04-15 | 1973 | 1 | |
| Olympia Theatre | Olympia Theatre | Ireland, Dublin, 72 Dame St | 1954-07-05 | -- | 1954 | 1 | |
| Ottumwa | Ottumwa | United States of America, Ottumwa | 1903-11-04 | 1903-11-04 | 1903 | 1 | |
| Oberlin College & Conservatory, Hall auditorium | Oberlin College & Conservatory | United States of America, Oberlin, 67 North Main St. | 2014-04-17 | 2014-04-19 | 2014 | 1 | |
| Old Red Lion Theatre | Old Red Lion Theatre | England, London, 418 St John Street | 2000-10-17 | 2000-11-11 | 2000 | 1 | |
| Opéra National de Lyon | Opéra National de Lyon | France, Lyon, 1 place de la Comédie | 2022-06-04 | 2022-06-13 | 2022 | 1 | |
| Odeon | Odeon | Argentina, Buenos Aires | 1904-06-24 | 1904-06-26 | 1904 | 1 | |
| Óbudai Kisfaludy Színház | Óbudai Kisfaludy Színház | Hungary, Budapest | 1900-04-15 | -- | 1900 | 1 | |
| Opera House | Opera House | United States of America, Logan | 1905-04-15 | 1905-04-15 | 1905 | 1 | |
| Olavskapellet, Borgarsyssel Museum | Olavskapellet, Borgarsyssel Museum | Norway, Sarpsborg, Gamlebygaten 8 | 2006-08-01 | 2006-08-02 | 2006 | 1 | |
| Ōsaka Chikamatsu-za | Ōsaka Chikamatsu-za (Chikamatsuza Theatre) | Japan, Osaka | 1913-11-21 | 1913-11-25 | 1913 | 1 | |
| Opernzelt | Opernzelt | Germany, Heidelberg, Emil-Maier-Straße 16 | 2011-04-29 | 2011-07-05 | 2011 | 1 | |
| Oden Hall | Oden Hall | United States of America, Dr, Gambier, 107 College | 2024-04-07 | 2024-04-07 | 2024 | 1 | |
| Odda yrkesskule | Odda yrkesskule | Norway, Odda | 1970-01-23 | -- | 1970 | 1 | |
| Overture Center for the Arts, The Playhouse | Overture Center for the Arts, The Playhouse | United States of America, Madison, 201 State St | 2010-03-18 | 2010-03-28 | 2010 | 1 | |
| OSCO - Open Space Hannover | OSCO - Open Space Hannover | Germany, Hannover, Fössestraße 103 | 2019-11-14 | 2019-11-17 | 2019 | 1 | |
| Odeïon | Odeïon | Austria, Salzburg/Langwied, Waldorfstraße 13 | 2013-09-26 | 2013-10-27 | 2013 | 1 | |
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