Magnificat
... that a Magnificat was composed for the 1200th anniversary of Salzburg Cathedral in 1974 by Krzysztof Penderecki for two choirs of at least 24 voices, and conducted by him in the premiere?
... that a <b id="mwBTI"><a href="./Magnificat_(Penderecki)" id="mwBTM" rel="mw:WikiLink" title="Magnificat (Penderecki)">Magnificat</a></b> was composed for the 1200th anniversary of <a href="./Salzburg_Cathedral" id="mwBTQ" rel="mw:WikiLink" title="Salzburg Cathedral">Salzburg Cathedral</a> in 1974 by <a href="./Krzysztof_Penderecki" id="mwBTU" rel="mw:WikiLink" title="Krzysztof Penderecki">Krzysztof Penderecki</a> <i id="mwBTY">(pictured)</i> for two choirs of at least 24 voices, and conducted by him in the premiere?<!--Special occasion hook for December 8-->