Population 4.6 million. St. Petersburg is not technically on the Trans-Siberian railroad, but it only an overnight ride away from Moscow, and for traveling purposes one of the more interesting cities to be visited. Situated 10 degrees from the arctic circle. Founded in 1703, and a product of one man Peter the Great's  vision.
 A relatively young European city ( founded: 1703) and is highly distinguished
within Russia proper. A fascinating study for anyone interested in urban
planning, the layout of St. Petersburg is in complete constrast with its
natural landscape. It is a  highly organized grid system imposed on 40  swampy
islands. Moscow, conversely,  and most every other Russian city are the
products of organic growth and tend to be more circular in layout.
 Capital of the voluminous Russian Empire, home to the Romanov dynasty.
Because of its positioning, however, on the far outskirts of the country,
Petersburg was understandably second to Moscow as a terminus for commerical

link to:
St. Petersburg Times