Kazan is one of the largest Russian cities and one of the main tourist destinations. It is easily accessible by plane, train and car.
By plane: Kazan International Airport has direct connections to many major airports around the world. From there you can get to the city center by Aeroexpress train (travel time is 26 minutes) or by bus number 97.
By train: Kazan is a railroad hub (The Gorky Railway) taking a lot of trains from all over Russia (Siberia, the Far East, the Volga Region, and the Central part of Russia). There are several trains from Moscow that are available every day and multiple times a day (the travel time varies from 10 to 19.5 hours). There are also trains from St. Petersburg which will take about 22 hours to arrive to Kazan. The timetables and tickets are available on the Russian Railways website.