Babylon the Great was 1st century Rome. (As Jeffro said above)
Imperial Rome was personified as the goddess Dia Roma, which the Jews absolutely despised.
The parallels between the "seven hill upon which the woman sits" and the "many waters" she sits by are unmistakable in depictions of the goddess, such as you will find on the obverse side of Roman coins.
The premise of this book is a prophecy attributed to St. Malachy, centuries after he allegedly uttered it, so it's in a whole different league compared to JW writings on Revelation.
You might want to take a look at what other books these two wingnuts (Horn and Putnam) have written.