We are talking about Anne Boleyn, her daughter Elizabeth I, and Elizabeth’s glamorous rival Mary, Queen of Scots. To each of these ladies, Donizetti devoted a full-blooded bel canto masterpiece. The divas who have tackled all three, as Beverly Sills did in her glory, can be counted on the fingers of one hand. Three years ago, Sondra Radvanovsky aced the Triple Crown at the Met in a matter of months. In Chicago, she attempts something arguably even more spectacular: the climactic acts of Anna Bolena, Maria Stuarda, and Roberto Devereux back to back on a single program. —M.G.