Here are links to 2 versions of the map of the continent of the Flanaess, commonly known as the World of Greyhawk, after the continent's most famous city.
http://www.highprogrammer.com/alan/gaming/dnd/greyhawk/map/supermap.html
http://hometown.aol.com/dreadwood/maps/
The campaign is intended to start in the Free City of Irongate, which is located at this particular sub-map