Watch Online Free on Watchseries. Don Giovanni, opera in two acts by Wolfgang Amadeus Mozart (Italian libretto by Lorenzo da Ponte) that premiered at the original National Theatre in Prague on October 29, 1787. The opera’s subject is Don Juan, the notorious libertine of fiction, and his eventual descent into hell. For Mozart, it was an unusually intense work, and it was not entirely understood in his own time. Within a generation, however, it was recognized as one of the greatest of all operas. Presented by the Salzburg Marionette Theatre with narration provided by Sir Peter Ustinov.