The Whore of Babylon refers to a real physical place. The Bible tells where it is:

(Revelation 17:6-9 NIV) I saw that the woman was drunk with the blood of the saints, the blood of those who bore testimony to Jesus. When I saw her, I was greatly astonished. {7} Then the angel said to me: "Why are you astonished? I will explain to you the mystery of the woman and of the beast she rides, which has the seven heads and ten horns. {8} The beast, which you saw, once was, now is not, and will come up out of the Abyss and go to his destruction. The inhabitants of the earth whose names have not been written in the book of life from the creation of the world will be astonished when they see the beast, because he once was, now is not, and yet will come. {9} "This calls for a mind with wisdom. The seven heads are seven hills on which the woman sits.

Rome was built on seven hills. The woman riding the Beast is obviously the Catholic Church. The Catholic Church murdered millions of Christians. The Vatican truly is a synagogue of Satan.