| ORF Radio (Austria) | ORF Radio (Austria) | Austria | 1991-04-18 | -- | 1991 | 1 | |
| O'Reilly Theatre | O'Reilly Theatre | Ireland, Dublin, Great Denmark Street | 2011-09-27 | 2011-10-16 | 2011 | 1 | |
| Oslo Nye Teater (Centralteatret) | Oslo Nye Teater (Centralteatret) | Norway, Oslo, Akersgata 38 | 1972-09-28 | 2017-06-17 | 1972 - 2017 | 10 | |
| Opera House | Opera House | United States, Bemidji | 1904-09-20 | 1904-09-20 | 1904 | 1 | |
| Odense | Odense | Denmark, Odense | 1948-04-20 | -- | 1948 - 2000 | 2 | |
| Opole | Opole | Poland, Opole | -- | -- | | | |
| Oslo Domkirke | Oslo Domkirke | Norway, Oslo, Karl Johans gate 11 | 2018-02-09 | 2018-02-10 | 2018 | 1 | |
| Opéra National de Lorraine | Opéra National de Lorraine | France, Nancy, 1 Rue Sainte-Catherine, | 2013-05-23 | -- | 2013 | 1 | |
| Operahuset Nordfjord | Operahuset Nordfjord | Norway, Nordfjord, Sophus Lie-vegen 3 | 2009-11-09 | -- | 2009 - 2017 | 6 | |
| Opera House | Opera House | United States, Telluride | -- | -- | | | |
| Oslo | Oslo | Norway, Oslo | 1928-02-28 | 2008-10-02 | 1928 - 2014 | 9 | |
| Odeon-Theater | Odeon-Theater | Germany, Goslar, Bismarckstraße 1 | 1997-10-10 | 1997-10-10 | 1997 - 2005 | 2 | |
| Odenkirchen | Odenkirchen | Germany, Odenkirchen | 1893-10-07 | -- | 1893 | 1 | |
| Omaha | Omaha | United States, Omaha | 1903-11-05 | 1903-11-05 | 1903 | 1 | |
| Ogra | Ogra | Romania, Ogra | -- | -- | | | |
| Orkdal Kulturhus | Orkdal Kulturhus | Norway, Orkanger, Orkanger | 2012-11-11 | 2015-10-09 | 2012 - 2015 | 4 | |
| Ohio State University | Ohio State University | United States, Columbus, 1739 North High Street | 1981-02-27 | 2001-03-04 | 1981 - 2001 | 2 | |
| Ohkuma Auditorium | Ohkuma Auditorium | Japan, Tokyo, Japan | 1954-09-11 | -- | 1954 - 1965 | 3 | |
| Oberlin College & Conservatory, Hall auditorium | Oberlin College & Conservatory | United States, Oberlin, 67 North Main St. | 2014-04-17 | 2014-04-19 | 2014 | 1 | |
| Opera House | Opera House | United States, Racine | 1903-05-06 | 1903-05-06 | 1903 | 1 | |
| Oosterpoort Groningen, De | De Oosterpoort Groningen | Netherlands, 9724 DA, Trompsingel 27, | 2000-04-20 | 2000-04-21 | 2000 | 1 | |
| Old Vic, The | The Old Vic | England, London, The Cut | 1922-03-06 | 2016-03-19 | 1922 - 2016 | 11 | |
| Opera Comique Theatre | Opera Comique Theatre | England, London | 1889-07-17 | 1895-03-30 | 1889 - 1895 | 6 | |
| Olten | Olten | Switzerland, Olten | 2003-02-17 | -- | 2003 | 1 | |
| Ostadetheater | Ostadetheater | Netherlands, Amsterdam | 1985-04-25 | -- | 1985 | 1 | |
| Oranienburg | Oranienburg | Germany, Oranienburg | -- | -- | | | |
| Observatoriet | Observatoriet | Norway, Oslo, Observatoriegata 1 | 2007-06-12 | 2007-08-17 | 2007 - 2013 | 2 | |
| Ogólnopolski Festiwal Sztuki Reżyserskiej INTERPRETACJE | Ogólnopolski Festiwal Sztuki Reżyserskiej INTERPRETACJE | Poland, Katowice, Sejmu Śląskiego 2 | 2016-11-12 | 2016-11-12 | 2016 | 1 | |
| Odeon Theatre | Odeon Theatre | United States, St. Louis | 1905-10-04 | 1912-03-27 | 1905 - 1912 | 2 | |
| 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 | |
| Oskar-Herbig-Halle | Oskar-Herbig-Halle | Germany, Mellrichstadt, Bahnhofstr. 17 | 2004-03-03 | -- | 2004 - 2011 | 2 | |
| Opernhaus Chemnitz | Opernhaus Chemnitz | Germany, Chemnitz, Theaterstraße 2 | 1927-09-27 | -- | 1927 - 1991 | 4 | |
| Osnabrücker Stadttheater | Osnabrücker Stadttheater | Germany, Osnabrück, Große Gildewart 7 | 1894-03-29 | 1900-04-26 | 1894 - 1909 | 7 | |
| Onafhankelijk Toneel | Onafhankelijk Toneel | Netherlands, Rotterdam, Sint-Jobsweg 3 | 1998-05-21 | 2009-11-22 | 1998 - 2009 | 4 | |
| Oslo Public Library | Oslo Public Library | Norway, Oslo, Arne Garborgs plass 4 | 1988-06-30 | -- | 1988 | 1 | |
| Opera House | Opera House | United States | 1903-12-10 | 1903-12-10 | 1903 | 1 | |
| Opera House | Opera House | United States, San Bernardino | 1903-12-31 | 1908-12-04 | 1903 - 1908 | 2 | |
| Oskarshamn | Oskarshamn | Sweden, Oskarshamn | 1991-05-03 | 1991-05-03 | 1991 - 1992 | 2 | |
| Odeon | Odeon | Argentina, Buenos Aires | 1904-06-24 | 1904-06-26 | 1904 | 1 | |
| Olomouc | Olomouc | Czech Republic, Olomouc | 2007-05-17 | -- | 2007 | 1 | |
| Odense Folketeater | Odense Folketeater | Denmark, Odense | 1907-10-29 | 1907-11-15 | 1907 - 1908 | 7 | |
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Venues
