Revelation 17:9

(16) And here [is] the mind which hath wisdom. The (c) seven heads (17) are seven mountains, on which the woman sitteth.

(16) An exhortation preparing for the readers in the same argument, as that of Christ "He that hath ears to hear let him hear". I would rather read in this passage "Let there be here a mind, etc". So the angel passes to the second place of this description.

(c) Children know what the seven hilled city is, which is so much spoken of, and where of Virgil thus reports, "And compasses seven towers in one wall", that city it is, which when John wrote these things, had rule over the kings of the earth. It was and is not, and yet it remains to this day, but it is declining to destruction.

(17) This is the description of the beast by things present (as I said before) by which John endeavoured to describe the same, that he might be both known of the godly in that age, and be further observed and marked of posterity afterwards. This delineation has one tip, that is, his heads, but a double description or application of the type: one permanent, from the nature itself, the other changeable, by the working of men. The description permanent, is by the seven hills, in this verse, the other that flees, is from the seven kings, (Revelation 17:10). Here it is worthy to be observed, that one type has sometime two or more applications, as seems good to the Holy Spirit to express, either one thing by various types, or various things by one type. So I noted before of the seven spirits in See Revelation 1:4. Now this woman that sits on seven hills, is the city of Rome, called in times past by the Greeks, "upon a hill" i. of seven tops or crests and by Varro, "septiceps" i. of her seven heads (as here) of seven heads, and by others, "septem collis" i. standing upon seven hills.