Cork Opera house was originally built in 1855, although its existence has not been continuous; having survived the burning of much of Cork city by British forces in reprisal for an ambush of a military convoy in 1920 by Irish rebels, the Opera House nevertheless was burned down in its centennary year by a combination of old wiring and wooden materials.
Although Cork had until then boasted the presence of a proper theatre in some form for over 250 years, it wasn't until 1963 that the Opera House was rebuilt fully and opened.
More recently, in 2003, large scale renovation works were completed on both the facade of the building and the surrounding Emmet Square .
Built, according to its original architect Sir John Benson, for the "promotion of science, literature and the fine arts, and the diffusion of architectural knowledge," the Opera House has always housed far more than just Opera. Performances of all types are a part of its history and current repertoire, and locals find both its range and lack of affiliation with multinationals such as Ticketmaster make a refreshing change.
A more detailed if florid history can be found at http://www.corkoperahouse.ie/about/history.htm, while http://www.corkoperahouse.ie/ has general information, bookings, etc.
http://www.irish-architecture.com/architects_ireland/benson.html has information on Sir John Benson's other works in Cork and Ireland.