Errr.... both. Given that it spreads across something like 11 timezones and is nearly twice the size of the second largest country in the world, any one continent would have trouble containing it. Tradition says that the border between Europe and Asia is the Ural mountain range, meaning the more populated ares of the country are in Europe while Siberia, Khamchatka etc lie in Asia. In effect, draw a line north of the west coast of the Caspian Sea: Europe on the left, Asia on the right. (Russia is a member of Uefa for football purposes and of the Eurovision Song Contest...)