By comparison, the Romans and imperial Chinese were pikers; the Soviet Union in its prime was the poorest of runners-up; even the British, at the moment when the sun theoretically never set on their empire, didn't compare. The U.S. has hundreds of military bases ranging in size from small American towns to tiny outposts across the planet, and yet you could spend weeks, months, years paying careful attention to the media here and still have no idea that this was so. Though we garrison the globe in a historically unprecedented way, that fact is not part of any discussion or debate in this country; Congress doesn't hold hearings on global basing policy; reporters aren't sent out to cover the subject; and presidents never mention it in speeches to the nation. Clearly, nothing is to be made of it.
It's true that, if you're watching the news carefully, you will find references to a small number of these bases. In the present Korean crisis, for instance, there has been at least passing mention of Washington's bases in South Korea (and the danger that the American troops on them might face), though often deep in articles on the subject. If, to pick another example, you were to read about the political situation in Bahrain, you might similarly find mentions of the U.S. base in that small Gulf kingdom that houses the Navy's Fifth Fleet. Generally, though, despite the millions of Americans, military and civilian, who have cycled through American bases abroad in recent years, despite the vast network of them (the count is now approximately 800), and despite the fact that they undergird American military policy globally, they are, for all intents and purposes, a kind of black hole of non-news.