Babylon in Revelation
"This is the first reference to Babylon in Revelation, though the details regarding Babylon’s offense and judgment will be dealt with at great length in chapters 17 and 18. Gaebelein writes: “This is an anticipative announcement of what will also happen as the great tribulation nears its close.” Ryrie writes that
the repetition of “is fallen” emphasizes the certainty of the utter destruction of Babylon. This is anticipatory since Babylon’s actual fall is connected with the outpouring of the seventh [bowl]...
Just as Babylon of old was the fountainhead of idolatry, so is mystic Babylon today the mother of all false religious teaching in Christianity. In the time of the end it will be headed up in one great false church—that worldly church, which has proved so unworthy and false to her Lord, is to be broken absolutely to pieces, to be utterly destroyed." 
So, in Revelation, Babylon may refer to a city that is the center of the new religion and politics of the world, but it certainly is symbolic of false teaching that is epitomized in the last days with the worship of the antichrist as God. False teaching has always been present and symbolized with Babylon (with an additional linguistic connection to Babel, where men also rebelled). This will reach a crisis point in the last days as almost all of the world worships the antichrist, but will also ultimately meet its demise at God's hand and with His wrath.