Peter and Paul Fortress is the place in which most of St. Petersburg is centered. The Fortress was built originally to protect land from the Swedes. However, the Swedes were beaten before the fortress was completed. There were so many things to do and see here! In the center of the fortress stands the SS Peter and Paul Cathedral. It is here that every Tzar from Peter the Great to Alexander III are buried except for Nicholas II. The interior of the Cathedral is absolutely amazing. One of the first you see when you walk in the front are the tombs of Peter the Great and Catherine I. Everything in this Cathedral resembles royalty in the highest form. As you move through the Cathedral you will approach something like a coin museum of some type.
Also in the fortress is a prison that you are able to tour. The prison is called Trubetskoi Bastion At one time it held some of the most dangerous political prisoners of Russia. These included, the Decembrists, Dostoevsky, Lenin's brother, and the writer Maxim Gorky. I actually stood in the cell that Lenin’s brother once spent his days. The prison is dark and gloomy. The cells contained nothing but a metal bed and table and a tiny window.
Among other things to see, is the statue of Peter the Great with a very tiny head. This statue was at one time the center of a huge controversy, because of the size of Peter's Head. I found that many Russians want to get pictures of them sitting in Peter the Great's Lap. So I figured, "When in Rome..." Also there is an area where you can walk along the top of the fortress. If you have time I would suggest doing it. You will get a great view of the city with the Neva River right below you. I grabbed some Russian Bliny (similar to pancakes) and ate at the top looking out at this great city.