If the Bible is its own best interpreter of symbolic terms then I can clearly tell you who she is not.
1. She is not the GOVERNMENT of Rome as "she" rides on the back of what symbolizes goverments - beast - beasts are used in Daniel for world governments - Dan. 7
2. She is not SECULAR Rome as she is called "Mystery Babylon" which refers to the "mystery religions" of Ancient Babylon. Additionally, she holds a cup full of "abominations" that symbolizes her religious philosophies as she traffics in "souls" - Rom. 17:1-5; 18:4,13 - as she is
the habitation of devils, and the hold of every foul spirit, and a cage of every unclean and hateful bird. -Rev. 18:2-3
3. She continues to the final "hour" when the Beast with ten kingdoms turn and destroy her before they engage the King of Kings which was future from John's day - Rev. 17:15-17
4. She is representative of something that God and all heaven hates and her destruction is the cause of rejoicing in heaven - Rev. 19:1-4.
5. She is Rome (Rev. 17:18) but not merely a literal city any more than the Lord's church is characterized as a literal "city" set on a hill.
6. She is set in contrast to the Lord's Church in Revelation 17-21.
a. Both are women ("harlot" versus "bride") - Rev. 17:5; 19:6
b. Both are cities (earthly versus heavenly) - Rev. 17:18; 21:1-26
c. Both contain true children of God - Rev. 18:4; Rev. 21:24
d. The Children of God she retains (Rev. 18:4) the Bride places outside the New Jerusalem (Rev. 21:24) and the children of God outsider her are inside the Bride (Rev. 19:6-7; 22:1-3).
7. She is polluted/perverted/ religion that forms an illicit union with secular governments that becomes inclusive of paganized Christianity
Alexander Hislop's "Two Babylons" is extremely well documented and N

NE has been able to overthrow his documented evidence that papal Rome is "mystery Babylon."