Downtown St Petersburg covers a vast area with its many districts and islands, each of which have their own characteristics. It's therefore difficult to define exactly where the city centre is. Even if you consider the main street, Nevsky Prospekt, as a candidate you have to bear in mind that the street is over four kilometres long and only runs through the southern half of the city. Others would suggest Palace Square with its central Alexander Column overlooked by the Winter Palace, the former Army HQ and the nearby St Isaac's Cathedral.
The official answer however is really rather simple. In the centre of the operations hall of the main post office, on Pochtamtskaya Ulitsa, is the pillar pictured with its prominent 0 and dated 1714. It was from this location that all distances from St Petersburg were measured. The post office was built in 1782-89 around this post, which was originally sited in its courtyard.
The post office is worth searching out in its own right, both as a fine example of the period architecture and for the various exhibitions it hosts. On my visit, this time round, there was an exhibition of Russian Olympics posters and stamps from the Moscow 1980 games.
As well as being a stunningly attractive building it is also perfectly functional, providing all the basic postal services and also offers public internet access. One thing I did miss out on though was taking pictures from outside - ach, well yet another reason why I have to revisit!
Exploring the Winter palace/Hermitage is a must when visiting St.Petersburg.
But take the trip to Pushkin (Tsarskoe Selo) as well to see the Catherine palace and the Alexander palace. Wonderful surroundings including the most beautiful English-style park with a lake. Idyllic!
Another two and a half miles from Pushkin is Pavlovsk.
Here you'll find an immense park, which is a masterpiece of sculpture and scenery.
This is the tomb of the famouse Russian Rock singer Victor Tsoi ('Kino'). He died in automobile accident in 1990. Now many of Russian singers (Zemfira, Mumii Troll, Checherina...) sing his songs.
It was his birthday at the end of June. There are always plenty of flowers and people on the Bogoslovskoje graveyard.
St. Petersburg is currently (Aug 2001) undergoing a major restoration program leading up to its 300th birthday in 2003 so many of its famous attractions are obscured by scaffolding etc.
If you want an unobscured view of these sites than maybe you should delay your trip until 2003
While I was in St. Petersburg, I witnessed a lot of wedding parties walking around town. Apparently it is a tradition for newly married couples to visit various monuments around town after the wedding ceremony.