Grand opera is a form of nineteenth century opera that generally features large casts and a large orchestra, fully or nearly fully sung dialogs, lavish and spectacular stage and costume design and effects, plots based on dramatic historic or mythological events, and four or five acts. Many, especially French ones, also include lavish ballet scenes. Perennially the most popular and most often performed grand operas by the Metropolitan Opera are the so-called "ABC's," namely Verdi's Aida, Puccini's La Boheme and Bizet's Carmen.