MADRID — Spanish soprano Montserrat Caballé, immortalized beyond the opera world by singing “Barcelona” with Freddie Mercury, died Saturday at the age of 85. She was admitted to Barcelona’s St. Pau Hospital in September with a gallbladder problem, having suffered a stroke in 2012.

Made in 1987 and intended to be sung at the opening ceremony of the 1992 Olympic Games, a plan frustrated by Mercury’s death a year before, “Barcelona” was a rare incursion into pop music by Caballé, and a showcase for the extraordinary power and beauty of her voice. But it has obscured, at least for a broader public, a career which established her as one of the opera greats of the 20th century.

She was born on April 13, 1933, in the working-class district of Gràcia in Barcelona. Caballé’s early career was a triumph of large talent over difficult circumstance. Taught music by her mother, she won a scholarship at the age of 11 to the Conservatorio Superior de Música del Liceo. She fainted during her graduation exam, debuted at the Liceo in 1962 with Richard Strauss’ “Arabella,” and stepped in to substitute for Marilyn Horne in Gaetano Donizetti’s “Lucrecia Borgia” at Carnegie Hall in 1965. Her performance confirmed her virtually overnight as one of the world’s great sopranos, a combination of Maria Callas and Renata Tebaldi, The New York Times announced.

Caballé’s achievement was not just to hit that pinnacle but stay at the top of the opera world for decades to come. She won special acclaim for her performances in Verdi and bel canto operas by playing such roles as Violetta in Verdi’s “La Traviata” or Elisabetta of Valois in his “Don Carlo.”

Those performances were both in the 1960s. The fact that by 1987, when she recorded “Barcelona,” she was no longer considered to be at the absolute height of her powers, gives an idea of the extraordinary talent she unleashed on the opera world.

Caballé is survived by a son and daughter. The latter, Montserrat Martí, also an operatic soprano, accompanied Caballé in her final public performance in 2014.