And the woman which thou sawest,.... Re 17:3 as there described,is that great city, often mentioned in this book; great Babylon, the city of Rome, Re 11:8 which reigneth over the kings of the earth; which then reigned in John's time over the kings of the earth; and this clearly points out the city of Rome, for there was no other city then, but that, which reigned over the kings of the earth; that was then the metropolis of the Roman empire, to which the whole world was subject; and therefore it is called all the world, Lu 2:1 and since, all the kings of the empire have been under the jurisdiction of Rome Papal.
It was formerly called Urbs Regum, a "city of kings" , either for the reason in the text, or because its inhabitants looked like kings. Justin. l. 18. c. 2.