From the historical standpoint, Revelation 18:21 points to the complete destruction and removal of what "Babylon" symbolized. While some see Babylon as Rome, from the fulfilled view, Babylon refers to Jerusalem under the Old Covenant system. Jesus called Jerusalem the city that kills the prophets (Matthew 23:37), and Revelation 18:24 says, "And in her was found the blood of prophets and of saints, and of all who have been slaughtered on the earth." This could only apply to Jerusalem (see also Luke 13:33-34).

When Revelation says Babylon "will never be found again," it is using finality language, like what we see in Jeremiah 51:63-64, where physical Babylon is thrown into the Euphrates to show its total end. Likewise, in Revelation 18:21, the imagery of the millstone shows a judgment from which there is no recovery.

From the covenantal standpoint, this means the Old Covenant system tied to the earthly Jerusalem, the temple, the priesthood, and the sacrificial law was completely and permanently ended. Hebrews 8:13 says, "When He said, 'A new covenant,' He has made the first obsolete. But whatever is becoming obsolete and growing old is about to disappear." That disappearance was completed in the destruction of Jerusalem in AD 70.

So the phrase "never be found again" does not refer to a literal city vanishing from the map, but to the permanent covenantal removal of apostate Jerusalem as the center of God's redemptive plan. It was replaced with the heavenly Jerusalem, the body of Christ, the New Covenant people (Hebrews 12:22-24).