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. St. Nicholas' Naval Cathedral, Saint Petersburg Conservatory, and Yusupov Palace are notable landmarks to explore if you're in the area. You can watch performances at Mariinsky Theatre, Alexandrinsky Theatre, and Oktyabrskiy Big Concert Hall if you're interested in local theater.