Fidelio (Op. 72) is a German opera with spoken dialogue in two acts by Ludwig van Beethoven. It is his only opera. The German libretto is by Joseph Sonnleithner. The opera tells how Leonore, disguised as a prison guard named "Fidelio", rescues her husband Florestan from death in a political prison.
As elsewhere in Beethoven's vocal music, the music is not especially kind to the singers. The principal parts of Leonore and Florestan, in particular, require great vocal skill and endurance in order to project the necessary intensity, and top performances in these roles attract admiration. This 1952 recording stars Christa Ludwig and Jon Vickers. Otto Klemperer conducts.