But it doesn't matter. Sure those countries were great and powerful, sure they have influenced the world in ways we can't imagine, or at least try to. But super power, is by it's definition, a modern phenomenon, hence no super power exists in pre-modern times. It is only by very loose definitions that ancient states are referred to as super powers (usually in popular-history TV documentaries, such as the ones the History Channel broadcast when they are not airing Ax Men or Ice Road Truckers), and this loose definition actually corresponds more or less to the definition for a great power. They use the term super power, because that is sure to cause the attention of viewers, because super power is thought of as "US powerful" in its language, it's the same reason they also use the words weapon of mass destruction and machine-gun, referring to balistae and longbows.Also despite the fact that the Roman Empire was "smallish" in total area, quite a big portion of the world's population at that time were in fact Roman subjects. In wiki there's a figure of 35.3% of world population in 2nd century AD as Roman subjects. Spanish Empire and various forms of Russia including under the Mongol rule are also very strong contenders.
But it is incorrect. Super powers are modern phenomenon, end of story. Rome was a great power, likely the most powerful in its time, but it was not a super power. Because super powers, and what is required for them to form, did not exist at the time.
I'm not an American...Only an American would say yes to this poll...
Only someone with no understanding of the definition and characteristics of super powers, would suggest any other countries than the US, the Soviet Union and the British Empire as candidates for the "Greatest super power in history".