There is one clue in Revelation that makes it obvious who is the only city that could be mystery Babylon in Revelation. Just as in the Old Testament where apostate Israel was called a harlot John says the same thing about Babylon. Only one city could be considered a harlot and that is Old Covenant Jerusalem. John Refers to Babylon as a prostitute that committed fornication in Rev. 17 and only one city could fit that description—Old Covenant Jerusalem. One would have to be in a covenant relationship with God in order to be able to commit fornication. Rome past or future is not in a covenant relationship with God so could never commit fornication. Only Jerusalem is in a position to commit fornication. This clearly puts the events of Revelation at the 70 AD destruction of Jerusalem.