Our 2 day stop in St. Petersburg was one of the best the entire cruise. The city is incredibly beautiful, and they have an amazing art collection. We had to go on a tour in order to get off the boat (since we didn't have visas) - so our first stop was the Hermitage - one of the top 3 art museums in the world.
Their collection is enormous, similar in size to the Louvre in Paris. Even the building was ornate, inside and out.
We saw several grand homes and churches including this classic onion dome church.
We also visited the Peterhof Palace (built to rival Versailles). I'd say they did a pretty good job with the competition.
While our tour was great at taking us to the "can't miss" sights, one surprising letdown was the food. They herded all of us into these 1,000 person tents where we were served meals with bland soup, horrible salad, these little fish egg appetizers, and some bitter/sweet berry dessert. Perhaps we got the real Russian experience with our meal - or perhaps the cruise line cheaped out on the food. Regardless, we had a great visit and would highly recommend the city to others. Just make sure you have a tour guide. The commentary about what it was like to live in pre and post communist Russia is truly thought provoking.