Verdi composed 'Un Ballo in Maschera' for the San Carlo Theatre in Naples where it was to have been staged during the 1858 carnival season. The libretto told the true story of the liberal King Gustavus III, who was shot in 1792 at a masked ball in Stockholm. For political reasons the action of the opera was relocated to the city of Boston. This historical solecism satisfied the authorities but due to the ridiculousness of the action in its American setting the opera failed to establish a place next to the more successful opera's of Verdi. Nowadays in many opera-houses the action has been restored to Sweden.