Many Northern European cruises include a stop in the Russian city of St. Petersburg. We were lucky to have it as an overnight, a great opportunity to spend time in this exciting city and explore its often tragic past. One thing I would recommend before you go is to learn a little bit about the Romanov dynasty, the Russian Revolution and the siege of Leningrad. This will put what you see in its historical perspective and help you better understand the people and culture of St. Petersburg.
In order to enter Russia you will have to have a temporary visitor’s visa. You can get one on your own by applying through an agency. There is a cost involved and you have to send away your passport (or copy of) with plenty of lead time to get the paperwork back before your leave. Any of the guidebooks I read gave detailed instructions on how to apply. A simple google search also provided a number of resources.
Or, and this is the best alternative, you can be part of a planned excursion. Doing so means that your visa is issued at the port and the cost is included in the excursion fee. 
If possible we will explore a port on our own, but in this case that was not a possibility so we eagerly embraced what the cruise line had to offer. We splurged on two full days of “The Best of St. Petersburg”. This was by any standards an expensive excursion but we really wanted to see all that we could while in this port. Even as expensive as we felt it was, getting our own visa and arranging a private excursion would have been just as expensive. And after experiencing traffic in the area, I was happy for the guaranteed return to the ship.
Our first day included a bus trip to Pushkin and a visit to Catherine’s Palace. The opulence of this royal home was at times overwhelming, but it was a pleasure to behold in all its splendor. We were lucky to have excellent guides who were well versed in the history of the palace.
From there we went to the Hermitage Museum (also known as the Winter Palace) back in St. Petersburg. Other than the Louvre in Paris I do not think there is a bigger, or better provided museum in the world. We did not have time to see all of it (you could not in one day) but we did see some of its most famous paintings by Old World masters such as DaVinci, Rembrandt and VanEyk, and sculptures by Michelangelo. We also had time to tour the Royal apartments to take in the furnishings and décor of this lavish home, and wonder at the mechanical genius of the peacock clock.
The second day we travelled to see Peterhof’s Grand Palace (also known as the Summer Palace and our home page panoramic ) with its 144 gravity feed fountains and beautiful gardens. The weather was amazing that day so we took advantage of it to stroll through the woods and gardens and to view some of the 200 plus statues.
From there we travelled back to the city to visit the Peter and Paul Fortress after a drive down the main street of Nevsky Prospekt and along the shore of the Neva River. There were plenty of photo opportunities. Lunch was included both days of our excursion. We were able to sample borscht, stroganoff and plenty of Russian vodka. Although the cruise line explained in advance that the portions were not what we were used to I found the meal more than ample.
Driving thorough the city one could not help but wonder what life was like under communism. Our guides Tatiana and Alexander answered many of our questions and shared personal aspects of their lives in St. Petersburg. One of the most moving was Tatiana telling us the story of her grandmother who had survived the German siege of then Leningrad during the Second World War. The only possession she had left was her sewing machine, which she fiercely protected as her only way of making money. Tatiana proudly explained that she still had that sewing machine, and that it still worked.
Our excursion was only one of the many available to choose from. We had friends who spent a day riding the subway and touring the markets to get an up close perspective of working class St. Petersburg. There were also a number of passengers that went ashore in the evening to see the ballet.
I hope that if you are able to visit St. Petersburg you too will embrace all that this fascinating city has to offer.