You might want to spend some time browsing the exhibits at Russian Museum, Anna Akhmatova Museum at the Fountain House, or Pushkin Flat-Museum. Great Gostiny Dvor, St. Michael's Castle, and Alexandrinsky Theatre are landmarks that you won't want to miss. You can watch performances at St. Petersburg Philharmonia, Mikhailovsky Theatre, and Bolshoi Saint Petersburg State Circus if you're interested in local theater.