In 1936, Nikolaidi traveled to
Vienna to compete in the Belvedere vocal competition. She placed fourth but earned a second hearing with the great conductor
Bruno Walter, which resulted in her being cast as Princess Eboli, a leading role, in
Verdi's opera
Don Carlos with the
Vienna State Opera on December 16, 1936. In 1948, Nikolaidi went to the United States with her husband and their son, Michael. She made her
Town Hall debut recital in
New York City in January 1949. The following morning, Jerome D. Bohm of the
New York Herald Tribune wrote: "In 20 years of music reviewing and in twice that number spent in listening to most of the world's best singers, I have encountered no greater voice or vocalist"; the
New York Times critic wrote of her "rare brilliance". She made her American operatic debut as Amneris in Verdi's
Aïda with the
San Francisco Opera and reprised the role for her
Metropolitan Opera debut in 1951 alongside the debut of
George London. In the early 1960s she retired from opera but continued concertizing extensively for a number of years. ==Teaching career==