You might want to spend some time browsing the exhibits at C-189 Submarine Museum, Erarta Museum and Galleries of Contemporary Art, or Pushkin Flat-Museum. Yusupov Palace, St. Petersburg Academy of Fine Arts, and Mariinsky Palace are well-known local landmarks worth a visit. You can watch performances at Mariinsky Theatre, St. Petersburg Philharmonia, and Alexandrinsky Theatre if you're interested in local theater.