Sandra Warfield performed with the Zurich Opera, where in 1961 she sang Katerina in the world premiere of Martinů's "The Greek Passion". They returned to the United States, and the Metropolitan Opera, in the 1960s. Her performances at the Met included Ulrica in Giuseppe Verdi's "Un ballo in maschera", Berta in "The Barber of Seville" by Gioachino Rossini, Marcellina in "The Marriage of Figaro", Maddalena in "Rigoletto" by Verdi and Erda in Richard Wagner's "Siegfried", totaling 172 performances. She sang the role of Delilah in "Samson and Delilah", with Richard Tucker performing as Samson. In her farewell performance in January 1972, Warfield
Rossini Opera Festival established in 1980 with the aim of making the world more aware of Rossini's neglected operas and presenting all of them in collaboration with the G. Ricordi & Co. music publishing house, which published their critical editions. Of the approximately three dozen operas written, only a handful are regularly presented. On 13 August 1993, the Italian parliament unanimously approved the Special Law N. 319 "Regulations in support of the Rossini Opera Festival", which recognizes the Pesaro Festival's achievements in the reviving of Rossini's operas as entitled to be included among the state-supervised works of restoration of the national artistic heritage.