Complex sentence: On May 21,1960, she made her first appearance at the Teatro alla Scala in Milan, again as Aida, becoming the first African American to sing a leading role in Italy's greatest opera house.
Split into simpler sentences: On May 21,1960, she made her first appearance at the Teatro alla Scala in Milan, again as Aida. She was the first African American to sing a leading role in Italy's greatest opera house.