You might want to spend some time browsing the exhibits at Erarta Museum and Galleries of Contemporary Art, C-189 Submarine Museum, or Military History Museum of Artillery. Strelka, Peter and Paul Fortress, and State Chamber Music Theater are monuments to see when you're exploring the area around Saint Petersburg's 300th Anniversary Park. You can wander around Alexander Garden, Alexandrovsky Park, or Kirov Park if you want a dose of fresh air.