| Ohgawara | Ohgawara | Japan, Ohgawara | -- | -- | | | |
| Opera House | Opera House | United States of America, Wyoming, Wyoming | -- | -- | | | |
| Ornö | Ornö | Sweden, Ornö | -- | -- | | | |
| Ogra | Ogra | Romania, Ogra | -- | -- | | | |
| Osimo | Osimo | Italy | -- | -- | | | |
| Ocna Sibiului | Ocna Sibiului | Romania, Ocna Sibiului | -- | -- | | | |
| Oppdal | Oppdal | Norway, Oppdal | -- | -- | | | |
| Opole | Opole | Poland, Opole | -- | -- | | | |
| Olivenza | Olivenza | Spain, Olivenza | -- | -- | | | |
| Odessa | Одеса (Odessa) | Ukraine, Odessa | -- | -- | | | |
| Oravice | Oravice | Slovak Republic, Oravice | -- | -- | | | |
| Opera House | Opera House | United States of America, Telluride | -- | -- | | | |
| Oranienburg | Oranienburg | Germany, Oranienburg | -- | -- | | | |
| Oituz | Oituz | Romania, Oituz | -- | -- | | | |
| Oulu | Oulu | Finland, Oulu | -- | -- | | | |
| Oddfellows' Hall | Oddfellows' Hall | Australia, Wagga Wagga, Fitzmaurice Street | -- | -- | | | |
| Ostróg | Ostróg | Poland, Ostróg | -- | -- | | | |
| Ornans | Ornans | France, Ornans | -- | -- | | | |
| Odder | Odder | Denmark, Odder | -- | -- | | | |
| Obârşia | Obârşia | Romania, Obârşia | -- | -- | | | |
| Opéra Orchestre national Montpellier Occitanie | Opéra Orchestre national Montpellier Occitanie | France, Montpellier, 11 Boulevard Victor Hugo | 2018-01-12 | 2018-01-13 | 2018 | 1 | |
| Oslo Nye Dukketeater | Oslo Nye Dukketeater | Norway, Oslo | 1994-08-23 | -- | 1994 | 1 | |
| Oscarshall | Oscarshall | Norway, Oslo, Oscarshallveien | 2017-08-28 | 2017-11-28 | 2017 | 1 | |
| Ontmoetingscentrum d'Iefte | Ontmoetingscentrum d'Iefte | Belgium, Deerlijk, Hoogstraat 122 | 2002-01-14 | 2002-01-15 | 2002 | 1 | |
| On Pitch Performing Arts CenterOn Pitch Performing Arts Center | On Pitch Performing Arts Center | United States of America | 2023-09-15 | 2023-09-20 | 2023 | 1 | |
| Överkalix Folkets Hus | Överkalix Folkets Hus | Sweden, Överkalix, Bulandsgatan 2 | 2010-11-16 | -- | 2010 | 1 | |
| Orkdal Samfunnshus | Orkdal Samfunnshus | Norway, Fannrem | 1978-11-22 | -- | 1978 | 1 | |
| Oscar Theatre | Oscar Theatre | Ireland, Dublin | 1980-04-07 | 1980-04-19 | 1980 | 1 | |
| Oravais Teater | Oravais Teater | Finland, Kimo, Oravais, Kyroboas Kvarn | 1996-07-11 | -- | 1996 | 1 | |
| Ovalhouse | Ovalhouse | England, London, 52-54 Kennington Oval | 2018-05-17 | 2018-05-19 | 2018 | 1 | |
| Old Courtroom, The | The Old Courtroom | England, Brighton, 118 Church St, Brighton and Hove | 2012-05-10 | 2012-05-13 | 2012 | 1 | |
| Opéra-Théâtre i Avignon | Opéra-Théâtre i Avignon | France, Avignon, 1 Rue Racine | 2012-07-18 | 2012-07-25 | 2012 | 1 | |
| Olofström | Olofström | Sweden, Olofström | 1992-11-12 | -- | 1992 | 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 | |
| Osses, Théâtre des | Théâtre des Osses | Switzerland, Givisiez, Place des Osses 1 | 2011-02-10 | 2011-02-27 | 2011 | 1 | |
| Orleneff’s Russian Lyceum | Orleneff’s Russian Lyceum | United States of America, New York, East Third Street | 1906-01-03 | -- | 1906 | 1 | |
| Ogólnopolski Festiwal Sztuki Reżyserskiej INTERPRETACJE | Ogólnopolski Festiwal Sztuki Reżyserskiej INTERPRETACJE | Poland, Katowice, Sejmu Śląskiego 2 | 2016-11-12 | 2016-11-12 | 2016 | 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 | |
| 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 | |
| Oviedo | Oviedo | Spain | 1904-- | -- | 1904 | 1 | |
| Olavskapellet, Borgarsyssel Museum | Olavskapellet, Borgarsyssel Museum | Norway, Sarpsborg, Gamlebygaten 8 | 2006-08-01 | 2006-08-02 | 2006 | 1 | |
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