The city is described as "seven mountains" (these are not literal mountains, but are the seven "heads" of the Beast - that is, the seven empires of history which controlled Israel - Assyria, Egypt, Babylon, Medo-Persia, Greece, Rome, and the empire of the Antichrist, the Revised Roman Empire - v. 9-10). Many have seen the "woman" to be the Roman Catholic Church, because it is in the Vatican, the very heart of modern Rome, and has influence all over most of the world. I seriously doubt this, as the Roman Catholic Church was not around during the first five empires.
And, even though many of their teachings are false, especially by adding works to the Gospel for salvation, it impossible for me to believe that the False Prophet would be compatible with a church which certainly would not worship the Beast (Rev. 13:11-18). On the other hand, the born again believers within the Roman Catholic Church will have been removed from this world via the Rapture (Jn. 14:1-3; 1 Thes. 4:13-18). And since the majority of professing Christians in all of the world's denominations will still be here expecting Christ, the remainder of Roman Catholics, like the Jews, may see the Antichrist as the Lord's Second Coming. Now that is very possible! And yet, I find it impossible to believe that "she" could be associated with the Beast, who is said to be "full of names of blasphemy" (v. 3)!
Stay tuned! I am still wanting to please my Lord (2 Tim. 2:15)!