| Oituz | Oituz | Romania, Oituz | -- | -- | | | |
| Ohkuma Auditorium | Ohkuma Auditorium | Japan, Tokyo, Japan | 1954-09-11 | -- | 1954–1965 | 3 | |
| Ohio State University | Ohio State University | United States of America, Columbus, 1739 North High Street | 1981-02-27 | 2001-03-04 | 1981–2001 | 2 | |
| Oerol Festival | Oerol Festival | Netherlands, Terschelling | 2014-06-13 | 2016-06-18 | 2014–2016 | 2 | |
| Olympic Theatre | Olympic Theatre | United States of America, St. Louis | 1891-01-11 | 1910-04-03 | 1891–1910 | 7 | |
| Opéra de Dijon | Opéra de Dijon | France, Dijon, 11 Boulevard de Verdun | 2014-03-10 | 2014-03-12 | 2014 | 1 | |
| Olivier Theatre | Olivier Theatre | England, Southbank, London, National Theatre, Upper Ground | 1978-04-25 | 2019-10-08 | 1978–2019 | 11 | |
| Oslo Nye teater | Oslo Nye Teater (Hovedscenen) | Norway, Oslo, Rosenkrantz' gate 10, Oslo, Norway | 2023-06-08 | 2023-08-24 | 2023 | 1 | |
| Old Town Hall Arts Center | Old Town Hall Arts Center | England, Hertfordshire, Hemel Hempstead | 1985-02-18 | 1985-02-20 | 1985–2011 | 2 | |
| Odense Teater | Odense Teater | Denmark, Odense, Jernbanegade 21 | 1928-04-30 | 2024-11-23 | 1928–2024 | 17 | |
| Olympia Theatre | Olympia Theatre | Ireland, Dublin, 72 Dame St | 1954-07-05 | -- | 1954 | 1 | |
| Oskar-Herbig-Halle | Oskar-Herbig-Halle | Germany, Mellrichstadt, Bahnhofstr. 17 | 2004-03-03 | -- | 2004–2011 | 2 | |
| Opéra-Théâtre i Avignon | Opéra-Théâtre i Avignon | France, Avignon, 1 Rue Racine | 2012-07-18 | 2012-07-25 | 2012 | 1 | |
| Ottumwa | Ottumwa | United States of America, Ottumwa | 1903-11-04 | 1903-11-04 | 1903 | 1 | |
| O'Connell Theatre | O'Connell Theatre | United States of America, Dekalb, Stevens Building, School of Theatre and Dance Northern Illinois University | 2009-02-19 | 2009-03-01 | 2009 | 1 | |
| Opera House | Opera House | United States of America, Racine | 1903-05-06 | 1903-05-06 | 1903 | 1 | |
| Oranjerie | Oranjerie | Netherlands, Roermond, Kloosterwandplein 12-16 | 2009-11-07 | -- | 2009 | 1 | |
| Opera House | Opera House | United States of America, Pensacola | 1903-10-25 | 1903-10-25 | 1903 | 1 | |
| Oddemarka skole | Oddemarka skole | Norway, Kristiansand, Kristiansand | 2006-11-08 | -- | 2006 | 1 | |
| Oslo Public Library | Oslo Public Library | Norway, Oslo, Arne Garborgs plass 4 | 1988-06-30 | -- | 1988 | 1 | |
| Other Place, The | The Other Place | England, Stratford-upon-Avon, Warwickshire, Waterside | 1981-07-06 | 1982-07-30 | 1981–1996 | 4 | |
| Old Red Lion Theatre | Old Red Lion Theatre | England, London, 418 St John Street | 2000-10-17 | 2000-11-11 | 2000 | 1 | |
| OC De Buiting | OC De Buiting (Cultuur, gemeenschaps of ontmoetingscentrum) | Belgium, Beringen, Tessenderlosesteenweg 18 | 2007-11-29 | 2007-11-30 | 2007 | 1 | |
| Orleneff’s Russian Lyceum | Orleneff’s Russian Lyceum | United States of America, New York, East Third Street | 1906-01-03 | -- | 1906 | 1 | |
| Odeon de Spiegel | Odeon de Spiegel | Netherlands, Zwolle, Blijmarkt 25 | 2000-04-28 | -- | 2000–2008 | 2 | |
| Ovågen | Ovågen | Norway, Øygarden | 2005-09-04 | -- | 2005 | 1 | |
| Oblastnoi dramteatr Volgograd | Oblastnoi dramteatr Volgograd | Russia, Volgograd | 1948-10- | -- | 1948 | 1 | |
| Orkdal Kulturhus | Orkdal Kulturhus | Norway, Orkanger, Allfarveg 7300 | 2012-11-11 | 2020-10-29 | 2012–2020 | 5 | |
| Orosháza | Orosháza | Hungary, Orosháza | 1890-05-12 | -- | 1890–1926 | 6 | |
| Ódry Színpad | Ódry Színpad | Hungary, Budapest, Vas utca 2 | 1967-12-16 | -- | 1967–2017 | 3 | |
| Odin Teatret | Odin Teatret | Denmark, Holstebro, Særkærparken 144 | 2011-- | -- | 2011–2016 | 4 | |
| Opernzelt | Opernzelt | Germany, Heidelberg, Emil-Maier-Straße 16 | 2011-04-29 | 2011-07-05 | 2011 | 1 | |
| Opéra de Rouen | Opéra de Rouen | France, Rouen, 7 rue du Docteur Rambert | 2003-11-29 | 2003-11-30 | 2003 | 1 | |
| Örnsköldsvik | Örnsköldsvik | Sweden, Örnsköldsvik | 1989-10-02 | 1989-10-02 | 1989–1993 | 2 | |
| Odda yrkesskule | Odda yrkesskule | Norway, Odda | 1970-01-23 | -- | 1970 | 1 | |
| Opera House | Opera House | United States of America, New Ulm | 1905-01-15 | 1905-01-15 | 1905 | 1 | |
| Onde, L' | L'Onde | France, Vélizy-Villacoublay, 8 bis Avenue Louis Breguet | 2015-05-19 | 2018-01-19 | 2015–2018 | 2 | |
| Ouagadougou, Carrefour Internationale de Théâtre de Ouagadougou | Carrefour Internationale de Théâtre de Ouagadougou | Burkina Faso, Bilbalogho, Ouagadougou, Burkina Faso | 2002-07-13 | -- | 2002 | 1 | |
| Orăștie | Orăștie | Romania, Orăștie | 1911-02-16 | -- | 1911 | 1 | |
| Odenkirchen | Odenkirchen | Germany, Odenkirchen | 1893-10-07 | -- | 1893 | 1 | |
| Odéon-Théâtre de l'Europe | Odéon-Théâtre de l'Europe | France, Paris, 67 Rue Monsieur le Prince | 1993-03-12 | 2019-06-15 | 1993–2019 | 5 | |
| Odeïon | Odeïon | Austria, Salzburg/Langwied, Waldorfstraße 13 | 2013-09-26 | 2013-10-27 | 2013 | 1 | |
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