Un Ballo in Maschera

Un Ballo in Maschera (A Masked Ball) is an 1859 three act opera with a libretto by Antonio Somma.  Initially based on Eugène Scribe's libretto for Daniel Auber's 1833 five act opera Gustave III, ou Le bal masqué about the assassination in 1792 of King Gustav III of Sweden who was shot while attending a masked ball,  Verdi's version ran afoul of numerous censorship regulations in Naples, Rome, and France.  As a result, the opera underwent a series of significant transformations and title changes, among which include the eventual change in setting from Stockholm, Sweden to Boston, Massachusetts during the colonial era.  Taking over two years from commission to production, it became one of the most frustrating experiences of Verdi's career.