Harlequin costumes and a spinet inscribed with the command ‘Inexpert hand, touch me not!’ hint at centuries of Milanese musical drama, on and off stage. Portraits show Rossini apparently chatting up patrons, while Verdi seems troubled by mixed reviews, and Callas, ever the goddess, rises above it all. Your visit can include a glimpse of the theatre’s famed interior from a box and a backstage tour if you don’t clash with rehearsal time. The museum’s Livia Simoni Library beckons buffs who want more.