How many continents did the Roman empire cover?
Here are a number of maps of the Roman Empire.
http://www.google.com/search?hl=en&ie=ISO-8859-1&q=Map%2C+Roman+Empire&btnG=Google+Search
http://www.google.com/search?hl=en&ie=ISO-8859-1&q=Map%2C+Roman+Empire&btnG=Google+Search