Aida held an important place in the earlier years of Callas’s career, and in 1950 it brought her debut at La Scala, Milan, the theatre where she soon became reigning diva. That same year, she sang the role of the Ethiopian princess in Mexico City, arousing near-hysteria among the audience (and anger in the competitive tenor singing Radamès) by interpolating a stupendous top E flat at the end of the Triumphal Scene, which closes Act II of the opera. She repeated the feat on her return to Mexico the following year, when this live recording was made. This time, the Radamès was the celebrated, heroic-voiced Italian, Mario del Monaco, while the Mexican mezzo-soprano Oralia Domínguez made an opulent Amneris and Giuseppe Taddei, one of the leading Italian baritones of his time, sang a powerful Amonasro.