About the Books: The World
The books in A Song of Ice and Fire mostly take place on the fictional continents of Westeros and Essos, which are based on medieval Europe and eastern Asia respectively. Westeros, the continent were the majority of the events in the book take place, is around the size of South America, with a variety of environments as diverse as North America. Essos is the larger of the two continents, roughly the size of Asia. Essos is the much more ancient of the two continents, with a variety of ancient nations and empires. Civilization in Westeros is fairly ancient as well, but the first men in Westeros came from Essos and once there, did not achieve the level of prosperity that many places in Essos enjoy. Below is map detailing Westeros and the major castles and towns in it. Major locations are highlighted.
map_grrm_Westeros_large_color_with_highlights.JPG

"Map of Westeros." Gameofthrones.net. Gameofthrones.net, 20 March 2012. Web. 20 Mar 2012. <http://gameofthrones.net/resources/50-maps-of-westeros/537-map-of-westeros.html>.