| Ontmoetingscentrum d'Iefte | Ontmoetingscentrum d'Iefte | Belgium, Deerlijk, Hoogstraat 122 | 2002-01-14 | 2002-01-15 | 2002 | 1 | |
| Orosháza | Orosháza | Hungary, Orosháza | 1890-05-12 | -- | 1890 - 1926 | 6 | |
| Oppdal | Oppdal | Norway, Oppdal | -- | -- | | | |
| Opéra-Théâtre i Avignon | Opéra-Théâtre i Avignon | France, Avignon, 1 Rue Racine | 2012-07-18 | 2012-07-25 | 2012 | 1 | |
| Opera House | Opera House | United States, Pensacola | 1903-10-25 | 1903-10-25 | 1903 | 1 | |
| Orkdal Samfunnshus | Orkdal Samfunnshus | Norway, Fannrem | 1978-11-22 | -- | 1978 | 1 | |
| Opera House | Opera House | United States, New Castle | 1907-03-09 | 1907-03-09 | 1907 | 1 | |
| Obergrafschaft, Theater der | Theater der Obergrafschaft | Germany, Schüttorf, Hermann-Schlikker-Str. 1-3 | 2015-10-03 | -- | 2015 | 1 | |
| Oranjerie | Oranjerie | Netherlands, Roermond, Kloosterwandplein 12-16 | 2009-11-07 | -- | 2009 | 1 | |
| Opern- und Schauspielhaus Hannover | Opern- und Schauspielhaus Hannover | Germany, Hannover | 1920-06-21 | -- | 1920 - 1924 | 2 | |
| Oravais Teater | Oravais Teater | Finland, Kimo, Oravais, Kyroboas Kvarn | 1996-07-11 | -- | 1996 | 1 | |
| Oskarshamn | Oskarshamn | Sweden, Oskarshamn | 1991-05-03 | 1991-05-03 | 1991 - 1992 | 2 | |
| Opernhaus Chemnitz | Opernhaus Chemnitz | Germany, Chemnitz, Theaterstraße 2 | 1927-09-27 | -- | 1927 - 1991 | 4 | |
| Onafhankelijk Toneel | Onafhankelijk Toneel | Netherlands, Rotterdam, Sint-Jobsweg 3 | 1998-05-21 | 2009-11-22 | 1998 - 2009 | 4 | |
| Orkanger gymnas | Orkanger gymnas | Norway, Orkanger | 1970-02-13 | -- | 1970 | 1 | |
| Ocna Sibiului | Ocna Sibiului | Romania, Ocna Sibiului | -- | -- | | | |
| Oberschlesisches Grenzlandtheater Ratibor | Oberschlesisches Grenzlandtheater Ratibor | Poland, Ratibor / Racibórz | 1937-02-19 | -- | 1937 | 1 | |
| Opština Bečej | Opština Bečej | Serbia, Opština Bečej | 1903-03-11 | -- | 1903 | 1 | |
| Odeon | Odeon | Argentina, Buenos Aires | 1904-06-24 | 1904-06-26 | 1904 | 1 | |
| Odense Folketeater | Odense Folketeater | Denmark, Odense | 1907-10-29 | 1907-11-15 | 1907 - 1908 | 7 | |
| Ophelia Theater | Ophelia Theater | United States, Astoria, 21-12 30th Road | 2016-10-28 | 2016-11-13 | 2016 | 1 | |
| Odessa | Одеса (Odessa) | Ukraine, Odessa | -- | -- | | | |
| Orpheum Theatre | Orpheum Theatre | United States, Salt Lake City | 1908-06-13 | 1908-06-13 | 1908 | 1 | |
| Oravice | Oravice | Slovak Republic, Oravice | -- | -- | | | |
| Otta kulturhus | Otta kulturhus | Norway, Otta, Skansen 9 | 1993-03-07 | 2018-09-08 | 1993 - 2018 | 13 | |
| Other Place, The | The Other Place | England, Stratford-upon-Avon, Warwickshire, Waterside | 1981-07-06 | 1982-07-30 | 1981 - 1996 | 4 | |
| Old Auditorium, Worcester State College | Old Auditorium, Worcester State College | United States, Worcester, 486 Chandler Street | 1971-04-29 | 1971-05-01 | 1971 | 1 | |
| Opernhaus Graz | Opernhaus Graz | Austria, Graz, Opernring | 1912-05-24 | -- | 1912 | 2 | |
| Old Rep at Birmingham Repertory Theatre | The Old Rep at Birmingham Repertory Theatre | England, Birmingham | 2013-03-14 | 2013-03-28 | 2013 | 1 | |
| Opera House | Opera House | United States, McCook | 1905-03-16 | 1905-03-16 | 1905 | 1 | |
| Opéra de Rouen | Opéra de Rouen | France, Rouen, 7 rue du Docteur Rambert | 2003-11-29 | 2003-11-30 | 2003 | 1 | |
| Odense Theater | Odense Theater | Denmark, Odense, Sortebrødre Torv | 1876-04-20 | 1899-10-20 | 1876 - 1901 | 9 | |
| Olavshallen | Olavshallen | Norway, Trondheim, Kjøpmannsgata 44 | 1997-05-15 | 2008-02-29 | 1997 - 2008 | 5 | |
| Ocean Hotell | Ocean Hotell | Norway, Horten, Jernbanegata 1 | 2006-02-02 | -- | 2006 | 1 | |
| Old American Can Factory, The | The Old American Can Factory | United States, Brooklyn, 232 3rd Street | 2003-03-06 | 2003-06-07 | 2003 | 2 | |
| Ottumwa | Ottumwa | United States, Ottumwa | 1903-11-04 | 1903-11-04 | 1903 | 1 | |
| Opernhaus, Städtische Theater Karl-Marx-Stadt | Städtische Theater Karl-Marx-Stadt (Opernhaus) | Germany, Karl-Marx-Stadt (Chemnitz), Theaterplatz | 1956-04-29 | -- | 1956 | 1 | |
| Óbudai Kisfaludy Színház | Óbudai Kisfaludy Színház | Hungary, Budapest | 1900-04-15 | -- | 1900 | 1 | |
| Oulun Kaupunginteatteri | Oulun Kaupunginteatteri | Finland, Oulu, Kaarlenväylä 2 | 1963-- | 1972-04-27 | 1963 - 1985 | 3 | |
| Oddemarka skole | Oddemarka skole | Norway, Kristiansand, Kristiansand | 2006-11-08 | -- | 2006 | 1 | |
| Oddfellows' Hall | Oddfellows' Hall | Australia, Wagga Wagga, Fitzmaurice Street | -- | -- | | | |
| Opera House | Opera House | United States, San Juan | 1905-05-06 | 1905-05-06 | 1905 | 1 | |
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Venues
