I fully agree with your account regarding the Great City of Babylon the Great being Jerusalem, just a comparison of Matthew 23v35 with Revelation 18v24 is enough to show this, I have read however another interpretation of the 666 identity in that it describes the Seal of Soloman that the Isreailis call the Star of David and use on thier flag, interesting about the colour red as it was the Rothschilds who brought the six pointed star into use as the identifying mark of modern Isreal, and the name Rothschild literally means Red Shield.
The great power Babylon the GReat can wield over the Kings of the Earth manily comes from its control of international banking, the result of its collapse is outlined in Revelation 18 were the collapse of economy is described, so therefore noteworthy that the mark of the beast is also tied in with commerce in that nobody might buy or sell with out the mark.
If you go on Youtube and put Aaron Russo interview in the search box, you can hear his claim of friendship with Rockefeller family and thier plan for all monitary transactions to be performed through an embeded chip in your hand, that"nobody might buy or sell" without said chip.