The town centre is a vison fulfilled by Tsar Peter. Sweden had to be cleared out from the north shore of Neva and then all rich people of Russia had to build a palace there in order to stay in the upper class. From nothing there, in the borderline between Russia and Sweden 1703, 100 years later it was a magnificent town, and continued to grow until 1917. Luckily, there is not much Soviet architecture present i centre. Not
The Neva is about 500 m wide and that sets the size of everything. I did not rent a cycle but that could be a good idea if you want to come out from the centre for a while.
Don't miss the Heremitage, Peterhof, Peter-Paul fortress and the artillery museum.
The canal boats gives nice wievs but it seems to be hard to find someone giving service in other languages than Russian. The hard problem to find service in other language than Russian is a general problem.
If you are in to military history, try to get out to Kronstadt which now can be visited by foreigners.
Be there in the summer! The streets does not seem to have lights except in the very centre. It is dark in the winter but lovely in the summer. The white nights are really existing.