Sound of music was originally intended for Audrey Hepburn, but it went to Julie Andrews. Ironcially, My Fair Lady, which was being filmed around the same time, was originally intended for Julie Andrews. But it went to Hepburn. (Andrews was preoccupied with Mary Poppins and The Sound of Music.)

And no one can dispute that Andrews made the best Maria, and Hepburn made the best Eliza.