I believe they are all from this period.
Mussorgsky is an insane genius. Like I mentioned earlier, Boris Godunov is mind-blowingingly wonderful, and I agree, Khar, that St. John's Night on Bald Mountain or Night on Bare Mountain is a lot of fun...Although work still needs to be done to clear up misconceptions about his composing. He knew when he was doing the "wrong" thing, and used it for effect.
And there's a lot more to Carmina Burana than just "O Fortuna"
I was going to be sad that you don't like any Italian classical and then realized almost all of the Italian classical I like is opera, and, well, opera isn't for everybody.
As far as Italian opera goes, I love all the standards: Rossini, Puccini, and Verdi. Although, Verdi's Messa da Requiem isn't opera and is one of my favorite works right now.