The seven heads and seven mountains are the same thing. The seven “heads” are seven kings and the seven mountains are seven kingdoms. Kings were often referred to by their kingdoms, and vice versa. In Rev 17.10 it says “five have fallen” referring to Egypt, Babylon, Assyria, Medo-Persia and Greece, the “one is” refers to Rome and the “other has not yet come refers to Revived Rome in the last days and spoken about by Daniel the prophet.
The “he” in verse 10 is referring to the seventh kingdom. This kingdom will start out with ten kingdoms/kings but three will defect, leaving the seven. These are the ten toes of Nebuchadnezzar’s statue in Dan 2. But, in Rev 17.11 it talks about the “beast”, who is the False Messiah, who is also “an eighth” or the one who rules over all the other seven.
In Micah 5.5 there is a prophecy about these seven kings/kingdoms. It says that the Assyrians will invade Israel. Now, in prophecy, Assyria is a picture of the coming Russian invasion of Israel (Ezek 38-39). It then says that “we (Israel) will raise up against him (Gog/Russia) seven shepherds (kings) and eight leaders of men.” This refers to our passage in Revelation because there will be seven kingdoms/kings but one is “an eighth” (the False Messiah) ruling over these seven shepherds/kings/kingdoms.
Russia will invade Israel between Rosh ha Shannah and Yom Kippur at the end of the third year of the Tribulation, or Birth-pains. Europe, led by the False Messiah and seven nations (eight leaders of men-Micah 5.5) will be called on to help Israel because they agreed to a covenant of security for seven years three years earlier (Dan 9.24-27) but they will be of no help. God destroys the Russian army and her allies, but the False Messiah will be given credit for this destruction, opening the way for further deception as he moves into Israel.
Six months later he will declare himself God on Nisan 10 (2 Thes 2). So, this last kingdom will be the eighth. But, in addition, the False Messiah will also be “the eighth” which means that he will rule over the other seven kings/kingdoms, making him the eighth.
Some people interpret the seven mountains that Mystery Babylon sits on as Rome. But, let’s look at that. Mystery Babylon is a false religious system that has been around for a long time. The Catholic Church sits on Vatican Hill and it is not one of the seven hills of Rome. It did not belong to the ancient district of Rome nor was it included within the walls of Rome.
The seven hills of Rome are the Palatine, Capitoline, Quirinal, Aventine, Caelian, Esquiline and Viminal. Vatican hill is not one of the seven. Also, hills are not mountains and are not very high, only a few hundred feet. The mountains referred to in the book of Revelation are referring to kingdom/kings, as we have said above, and these held power over Israel at some time or another. Some also interpret Mystery Babylon as the United States.
These kingdoms are Egypt, Assyria, Babylon, Medo-Persia, Greece and Rome. Two are in the future, and they would be Revived Rome with ten nations, and the final configuration will be the seven nations after three defect. The Roman Catholic Church is not Mystery Babylon, but it is a part of it, along with other denominations. Mystery Babylon is just that, a system of false religion in many forms that will culminate in the religious power behind the False Messiah and the False Prophet.
This brings up the question about the Beast (False Messiah) suffering a mortal head wound (Rev 13.3). This is symbolic language and it does not mean that the False Messiah will be assassinated and come back to life. In Revelation 13.1, he sees a seven headed beast arising out of the sea. The sea is symbolic for the spirit world or unconverted humanity (Isa 57.20).
In Hebrew eschatology, this seven headed creature is called “Leviathan” and it is symbolic of the False Messiah (Isa 27; Psa 74; Job 41-check out the Jewish Encyclopedia on this subject). The seven heads correspond to the seven mountains /kingdoms of world nations already mentioned. The seventh nation will remain “for a short while.” Now, “one” of the seven heads (plural) was “slain.” That means Rome “fell” but his wound was “healed” (Rome will come back and be revived) but this will be temporary.
In other words, certain nations have arisen and they have held dominion over Israel and God’s people. The wounded “head” was Rome and being “healed” is referring to the fact that Rome will be “revived” in the last days and the geographical area that will make up this last kingdom will be the same area that was part of the old Roman Empire. It will start out with ten kingdoms, just like the Roman Empire was made up of ten divisions.
The ten toes of the image in Dan 2 reflect this “resurrection” of the Roman Empire after it fell (was slain). The “beast” is symbolic of the False Messiah and the seven kingdoms that will remain after three defect and these remaining seven kings will be in power when the Messiah returns on Yom Kippur and sets up the Kingdom of God forever (Dan 2.41-45). What is slain and revived is one of the kingdoms (Rome), no the literal head of the False Messiah.