Verdi: Aida (Complete Opera recorded in 1955)

One of the legendary moments in Callas's career came in 1950 in Mexico City, when she interpolated a stupendous top E flat at the end of the Triumphal Scene in Act II of Aida. In this recording under Serafin she abided by the score, but still prompted Gramophone to speak of her 'fascinating art and prodigious personality', observing the way she was 'rapt in imaginative intensity in the significance of the words'.