"Un ballo in maschera" is a somewhat unusual Verdi 1859 opera, in that it was initially based on a previous opera, by Daniel Auber - "Gustave III, ou Le bal Masque" -, with a libretto written by Eugene Scribe. That opera, had been concerned with the late 18C assassination of Gustav III, of Sweden.
Verdi transmuted his work, over a period of two years (much of it due to copyright issues and political tension), so that at one stage, the opera was concerned with a supposed assassination in Germany, and followed by the eventual subject, the assassination of the Earl of Warwick, in Boston, Massachussets, during British rule of the US.
Maria Callas' role in this 1956 recording, was as Amelia, the wife of the Secretary of the Earl of Warwick. The character is in love with the Earl.
Disc One :-
1) Prelude (4:19)
2)-9) Act I Scene I (17:00)
10)-21) Act I Scene II (29:50)
22)-27) Act II (beginning of only Scene ; 18:51)
Disc Two :-
1)-5) Act II (conclusion of only Scene ; 12:46)
6)-18) Act III Scene I (33:10)
19)-24) Act III Scene II (16:05)
Both CDs are in EX+ condition.