Choirs: Apart from church music, in which choral singing has always been a tradition, and the opera choirs, which were usually rather small until the 19th century, independent choirs only developed as the musical activities of the middle class became institutionalised. The newly founded musical associations usually comprised a music school and a choir (one of the most famous is the "Singverein" choir of the Society of the Friends of Music); along with bourgeois choir clubs, choral unions, which were of nationalist persuasion, also developed during the 2nd half of the 19th century. Today, there are small and large choirs pursuing various musical aims; the most famous amateur associations are: the Singverein, Singakademie, A. Schoenberg Chor and Concentus vocalis. Austria´s best known professional choir is the concert association of the Vienna State Opera Choir. Saengerbund.