London is one of the major classical and popular music capitals of the world and is home to major music corporations, such as EMI and Warner Music Group as well as countless bands, musicians and industry professionals. The city is also home to many orchestras and concert halls, such as the Barbican Arts Centre (principal base of the London Symphony Orchestra and the London Symphony Chorus), Cadogan Hall (Royal Philharmonic Orchestra) and the Royal Albert Hall (The Proms). London's two main opera houses are the Royal Opera House and the London Coliseum. The UK's largest pipe organ is at the Royal Albert Hall. Other significant instruments are at the cathedrals and major churches. Several conservatoires are within the city: Royal Academy of Music, Royal College of Music, Guildhall School of Music and Drama and Trinity Laban.

Answer this question, if possible (if impossible, reply "unanswerable"): What are the names of London's two primary opera houses?
the Royal Opera House and the London Coliseum