"Nessun dorma" ("None shall sleep") is an aria from the final act of Giacomo Puccini's frequently performed opera Turandot and is one of the best-known tenor arias in all opera. It is sung by Calaf, il principe ignoto (the unknown prince), who falls in love at first sight with the beautiful but cold Princess Turandot. However, any man who wishes to wed Turandot must first answer her three riddles; if he fails, he will be beheaded. In the aria, Calaf expresses his triumphant assurance that he will win the princess.