19. ἡ πόλις ἡ μεγάλη. Probably Jerusalem, as in chap. Rev 11:8. It seems pointless to suppose Babylon to be mentioned twice over: while on the other view there is a climax. Jerusalem is (or is to be) converted—she is the City of God again, yet even she is sorely shaken (cf. 1 St Peter 4:17): other cities are wholly overthrown: while the City of God’s Enemy is to receive something more than overthrow.
εἰς τρία μέρη. There is probably a reminiscence of Zec 14:4-5. If so, the earthquake probably isolates the western hill and completes the division of the eastern hill into two. It is just possible that there may be a reference to the three parties of John, Eleazar, and Simon, into which Jerusalem was divided at the time of its siege by Titus. We have seen (on Rev 11:13) that Jerusalem is to be converted at the very last: but Rev 11:7-8 prove that this will not happen till the war with Antichrist is at least begun: consequently, this verse may be concerned with the judgement on Jerusalem still infidel.
αἱ πόλεις τῶν ἐθνῶν. Distinguished from Jerusalem on the one hand and from Babylon on the other.