Sydney Philharmonia Choirs is Australia’s largest choral organisation. It presents its own annual concert series in the Sydney Opera House the City Recital Hall, and other venues in New South Wales, as well as serving as chorus for the Sydney Symphony Orchestra. Formed in 1920, it currently comprises the following choirs: The Sydney Philharmonia Chamber Singers, formerly the Sydney Philharmonia Motet Choir; a chamber choir of around 32 voices The Sydney Philharmonia Symphony Chorus; a choral orchestral choir of 100 voices Vox; a youth vocal ensemble for 16- to 30-year-olds The Sydney Philharmonia Festival Chorus; a very large, choral orchestral, open choir of up to 450 voices ChorusOz; an un-auditioned choir formed annually to rehearse and perform a single major choral work over the course of a long weekend. Massed Choir; or Messiah Choir – an un-auditioned choir formed annually to rehearse and perform performances of Handel's Messiah in December