[5] Her voice was noted for its overwhelming force, bountiful reserves of power, and the gleaming brilliance and clarity in the upper register.

She studied with Ragnar Blennow in Åstorp for six months to prepare for an audition at the Royal Swedish Academy of Music in Stockholm where she came in first out of a group of 47 singers and was awarded the Christina Nilsson scholarship named for the famous soprano.

"[5] In 1946, Nilsson made her debut at the Royal Swedish Opera in Stockholm with only three days' notice, replacing the ailing singer scheduled for the role of Agathe in Carl Maria von Weber's Der Freischütz.

In Stockholm she built up a steady repertoire of roles in the lyric-dramatic field, including Donna Anna in Don Giovanni, Aida, Lisa in The Queen of Spades (opera), Tosca, Venus in Tannhäuser, Sieglinde in Die Walküre, Senta in Der fliegende Holländer and the Marschallin in Der Rosenkavalier, one of her favourite roles, all sung in Swedish.

She took the title role of Turandot, which is brief but requires an unusually big sound, to La Scala in Milan in 1958, and then to the rest of Italy.

Nilsson made her American debut as Brünnhilde in Wagner's Die Walküre in 1956 with the San Francisco Opera.

She attained international stardom after a performance as Isolde at the Metropolitan Opera in New York City in 1959, which made front-page news.

She said that the single biggest event in her life was being asked to perform at the opening of the 180th season at La Scala as Turandot in 1958.

However Nilsson claims her "explosive" high notes that were her biggest asset on-stage "have not been recorded like they should have been" in the studio.

The New York Times' review of the production's 8 March opening night is reprinted in the Metropolitan Opera Archives.

When Nilsson first arrived at the Met to rehearse the production of Die Walküre conducted by Karajan, she said, "Nu, where's Herbie?"

And Karajan once sent Nilsson a cable several pages long, proposing in great detail a variety of projects, different dates and operas.

[14] There was a healthy competition between Nilsson and tenor Franco Corelli as to who could hold the high C the longest in Act II of Turandot.

Bing, who knew how to handle Corelli's tantrums, suggested that he retaliate by biting Nilsson on the neck when Calaf kisses Turandot in Act III.

When long-time Metropolitan Opera director Sir Rudolf Bing was asked if she was difficult, he reportedly said "Not at all.

In a 1967 rehearsal of Die Walküre with Herbert von Karajan conducting, Nilsson responded to the gloomy lighting of the production by wearing a miner's helmet (complete with Valkyrian wings).

"[26] When Georg Solti, in Tristan und Isolde, insisted on tempos too slow for Nilsson's taste, she made the first performance even slower, inducing a change of heart in the conductor.

[27] Nilsson recorded all of her major roles in major commercial recordings of the complete works, as well as about a dozen solo recitals of arias, art songs, concerts, and hymns—all were originally released on vinyl LP format and most have been reissued on CD or in digital format.

Subsequently, she made fewer New York appearances than hoped in the early 1970s and was virtually excluded from the Salzburg Festival.

When she returned, Donal Henahan wrote in The New York Times, "The famous shining trumpet of a voice is still far from sounding like a cornet.

She played most of the other major soprano parts: Aida, Tosca, the Dyer's Wife in Strauss's Die Frau ohne Schatten, Salome, Elektra, Verdi's Lady Macbeth, and Leonore in Beethoven's Fidelio.

She retired in 1984 to her childhood home in the Skåne province of southern Sweden, where her father had been a sixth-generation farmer and she had worked to grow beets and potatoes until she was 23.

[31] She received the Illis quorum gold medal, today the highest award that can be conferred upon a Swedish citizen by the Government of Sweden.

[33] Nilsson died, aged 87, on 25 December 2005 at her home at Bjärlöv, a small village near Kristianstad in Skåne in the same county where she was born.

She was survived by her husband Bertil Niklasson (died March 2007), a veterinary surgeon whom she had met on a train and married in 1948.

On 20 February 2009, Spanish tenor Plácido Domingo was announced as the inaugural recipient of the prize, which carried with it a cash award of $1,000,000.

[36] The second winner of the Birgit Nilsson prize was Riccardo Muti,[37] who received the award in Stockholm on 13 October 2011.

[39] On 6 April 2011, the Bank of Sweden announced that Nilsson's portrait will feature on the 500 kronor banknote, beginning in October 2016.