| 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 | |
| Opera House | Opera House | England, Coventry, 4 Hales Street | 1911-09-11 | 1911-09-14 | 1911 | 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 | |
| Olathe Opera House | Olathe Opera House | United States of America, Olathe | 1908-01-31 | 1908-01-31 | 1908 | 1 | |
| Odeon | Odeon | Argentina, Buenos Aires | 1904-06-24 | 1904-06-26 | 1904 | 1 | |
| OSCO - Open Space Hannover | OSCO - Open Space Hannover | Germany, Hannover, Fössestraße 103 | 2019-11-14 | 2019-11-17 | 2019 | 1 | |
| Opéra National de Lorraine | Opéra National de Lorraine | France, Nancy, 1 Rue Sainte-Catherine, | 2013-05-23 | -- | 2013 | 1 | |
| Oda Tiyatrosu | Atatürk Kültür Merkezi Oda Tiyatrosu (AKM Oda Tiyatrosu) | Turkey, Istanbul, Gümüşsuyu Mahallesi, Tak-ı Zafer Cd., Beyoğlu | 1975-- | 1976-- | 1975 | 1 | |
| Opera House | Opera House | United States of America, San Juan | 1905-05-06 | 1905-05-06 | 1905 | 1 | |
| Oblastnoj teatr dramy | Oblastnoj teatr dramy | Russia, Novosibirsk, Bol'shevistskaya Ulitsa, 45 | 1987-11- | -- | 1987 | 1 | |
| Ostersund | Ostersund | Sweden, Ostersund | 1936-10-30 | -- | 1936 | 1 | |
| ONYX - Théâtre de Saint-Herblain | ONYX - Théâtre de Saint-Herblain | France, Saint-Herblain, 1 Place Océane | 2014-01-31 | -- | 2014 | 1 | |
| Oscarshall | Oscarshall | Norway, Oslo, Oscarshallveien | 2017-08-28 | 2017-11-28 | 2017 | 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 | |
| Opština Bečej | Opština Bečej | Serbia, Opština Bečej | 1903-03-11 | -- | 1903 | 1 | |
| Östersund | Östersund | Sweden, Östersund | 1879-- | -- | 1879 | 1 | |
| Oranjerie | Oranjerie | Netherlands, Roermond, Kloosterwandplein 12-16 | 2009-11-07 | -- | 2009 | 1 | |
| Odéon Théâtre de l'Europe | Odéon Théâtre de l'Europe | France, 75006 Paris, Place de l'Odéon | 2023-05-12 | 2023-06-09 | 2023 | 1 | |
| Orkdal Samfunnshus | Orkdal Samfunnshus | Norway, Fannrem | 1978-11-22 | -- | 1978 | 1 | |
| OC De Buiting | OC De Buiting (Cultuur, gemeenschaps of ontmoetingscentrum) | Belgium, Beringen, Tessenderlosesteenweg 18 | 2007-11-29 | 2007-11-30 | 2007 | 1 | |
| Ostadetheater | Ostadetheater | Netherlands, Amsterdam | 1985-04-25 | -- | 1985 | 1 | |
| Operetten Neues Theater, Central Theater | Operetten Neues Theater, Central Theater | Germany, Leipzig | 1910-08-23 | 1910-08-30 | 1910 | 1 | |
| Oslo Rådhus | Oslo Rådhus | Norway, Oslo, Rådhusplassen 1 | 2009-03-28 | -- | 2009 | 1 | |
| Oscar Theatre | Oscar Theatre | Ireland, Dublin | 1980-04-07 | 1980-04-19 | 1980 | 1 | |
| Opéra de Rouen | Opéra de Rouen | France, Rouen, 7 rue du Docteur Rambert | 2003-11-29 | 2003-11-30 | 2003 | 1 | |
| Opera House | Opera House | United States of America, New Ulm | 1905-01-15 | 1905-01-15 | 1905 | 1 | |
| Oblastnoi dramatičeskij teatr | Oblastnoi dramatičeskij teatr | Russia, Veliky Novgorod | 1948-09- | -- | 1948 | 1 | |
| Open Scene Orlando (Instagram) | Open Scene Orlando (Instagram) | United States of America, Orlando | 2020-05-07 | 2020-06-10 | 2020 | 1 | |
| Ogólnopolski Festiwal Sztuki Reżyserskiej INTERPRETACJE | Ogólnopolski Festiwal Sztuki Reżyserskiej INTERPRETACJE | Poland, Katowice, Sejmu Śląskiego 2 | 2016-11-12 | 2016-11-12 | 2016 | 1 | |
| Olten | Olten | Switzerland, Olten | 2003-02-17 | -- | 2003 | 1 | |
| Opéra national du Rhin | Opéra national du Rhin | France, Strasbourg, 19 place Broglie | 2020-09-19 | 2020-09-20 | 2020 | 1 | |
| Öteki Tiyatro | Öteki Tiyatro | Turkey, Maltepe/ANKARA, Gazi Mustafa Kemal Bulvarı No:114-C | 2007-06-23 | -- | 2007 | 1 | |
| Otto-Klenert-Schule | Otto-Klenert-Schule | Germany, Bad Friedrichshall, Rathausplatz 7 | 2006-02-18 | -- | 2006 | 1 | |
| Ontmoetingscentrum d'Iefte | Ontmoetingscentrum d'Iefte | Belgium, Deerlijk, Hoogstraat 122 | 2002-01-14 | 2002-01-15 | 2002 | 1 | |
| Opera House | Opera House | United States of America, Hopkinsville | 1904-11-23 | 1904-11-23 | 1904 | 1 | |
| Oberammergau, Passionstheater | Passionstheater Oberammergau | Germany, Oberammergau, Othmar-Weis-Str. | 2016-07-01 | 2016-07-23 | 2016 | 1 | |
| Ōsakafu Tachi josei sōgō sentā | Ōsakafu Tachi josei sōgō sentā (Osaka Prefectural Women's Center) | Japan, 1 Chome-3-49 Otemae, Chuo Ward, Osaka, 540-0008 | 2006-11-10 | -- | 2006 | 1 | |
| Obergrafschaft, Theater der | Theater der Obergrafschaft | Germany, Schüttorf, Hermann-Schlikker-Str. 1-3 | 2015-10-03 | -- | 2015 | 1 | |
| Opernhaus | Opernhaus | Germany, Essen | 1942-04-19 | -- | 1942 | 1 | |
| Olde Towne Hall Theatre | Olde Towne Hall Theatre | United States of America, North Ridgeville, 36119 Center Ridge Road | 2018-05-18 | 2018-05-19 | 2018 | 1 | |
| Old Rep at Birmingham Repertory Theatre | The Old Rep at Birmingham Repertory Theatre | England, Birmingham | 2013-03-14 | 2013-03-28 | 2013 | 1 | |
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