A major theme in the Gospels is, of course, the destruction of Jerusalem by Rome in 70 A.D. -- itself a vindication of Jesus' claim to be who he claims to be. I am increasingly comfortable with the notion that “Babylon the Great” (Rev 17.5ff) in John’s Revelation refers to Jerusalem, rather than to Rome. To be sure, Rome doesn't at all disappear -- it's the beast that Jerusalem rides in the passage. I.e., while related, the harlot and the beast do not refer to the same thing. See below, when the beast turns on the harlot.
A couple of tells:
 Rev 17.18. “The woman whom you saw is the great city . . .”
Rev 11.8, however, tells us that “the great city which mystically is called Sodom and Egypt” is “where also their Lord was crucified.”
Jesus was of course crucified in Jerusalem. Further, it is no more problematic to call Jerusalem “Babylon” than it is to call it “Sodom” and “Egypt.” The terminology underscores Jerusalem’s complete apostasy.
 “And in her was found the blood of prophets and of saints and of all who have been slain on the earth
” (18.24). (Cf., “The woman” is “drunk with the blood of the saints, and with the blood of the witnesses of Jesus” (17.6).)
Compare Rev 18.24 “all who have been slain on the earth” with Mt 23.35, “so that upon you may fall the guilt of all the righteous blood shed on earth
In context: “I am sending you prophets and wise men and scribes; some of them you will kill and crucify, and some of them you will scourge in your synagogues, and persecute from city to city, so that upon you may fall the guilt of all the righteous blood shed on earth, . . .Jerusalem, Jerusalem, who kills the prophets and stones those who are sent to her!” (Mt 23.34-35, 37).
 Rev 18.4 “I heard another voice from heaven, saying, "Come out of her
, my people, so that you will not participate in her sins and receive of her plagues.”
Compare Lk 21.20-21: "But when you see Jerusalem surrounded by armies, then recognize that her desolation is near. Then those who are in Judea must flee to the mountains, and those who are in the midst of the city must leave
, and those who are in the country must not enter the city; because these are days of vengeance, so that all things which are written will be fulfilled.”
 More generally, Rev 17.16 provides that the beast “hates the harlot and will make her desolate and naked, and will eat her flesh and will burn her up with fire.”
Rome turns on Jerusalem, and destroys the city. Jesus says to Jerusalem, “Behold, your house is being left to you desolate” (Mt 23.38). More generally, Jesus often prophesies of Jerusalem’s fall (Lk 21 & etc.).
There are other markers as well. But thinking more broadly – the OT prophets repeatedly compare Israel and Judah to harlots. Gentile nations and cities cannot be spiritual harlots because they weren't covenanted to God as Israel was.
Similarly, “And he cried out with a mighty voice, saying, ‘Fallen, fallen is Babylon the great! She has become a dwelling place of demons and a prison of every unclean spirit, and a prison of every unclean and hateful bird’” (Rev 18.2). This is not shocking for a Gentile city. It is shocking for Jerusalem. And it fulfills a prophecy that Jesus made in Mt 12.45:
“Then it goes and takes along with it seven other spirits more wicked than itself, and they go in and live there; and the last state of that man becomes worse than the first. That is the way it will also be with this evil generation."
Anyway, it seems to me to make more sense that “Babylon” refers to Jerusalem rather than to Rome.
The Revelation circles around Israel and Jerusalem. More broadly, I'd suggest it's centrally concerned with Jerusalem's destruction, which in turn serves to vindicate that Jesus was who he claimed to be (Lk 20.9-16, and etc.).