Moscow is obviously the big main city to visit being the capital and most populated off all places in Russia. Because of it's size it is considered a megacity and is the northernmost megacity in the world.
Formerly known as Leningrad, Saint Petersburg was changed back to it's original name in 1991. Most people drop the 'Saint' and it is widely know simply as Petersburg. A great city to visit and take in some culture with its 221 museums, 2000 libraries and more than 80 theatres.
Kazan is the capital and largest city of the Republic of Tatarstan and is one of Russia's big tourist spots thanks to its famous Kremlin which has people visiting from all over the world, staying in Kazan to view it.
Omsk is a prominent education centre for Russia and is a great place to visit for those looking for a more educational visit with a lot of museums, theatres and educational institutions to visit.