Chapters 17 and 18 are given to the apostle John outside the chronological flow of the 7 bowl judgments. They provide a flashback for orientation to "Babylon" which was judged at the 7th bowl.
The commentary by John Walvoord provides an accurate and valuable evaluation of both chapters.
I will stand on his shoulders and share his wisdom here so that on my site the reader can have access to it without having to look elsewhere.
Dr. Walvoord of course holds to the pretrib rapture position so I will make a few comments throughout in order to harmonize with the prewrath rapture position. But for the most part, the visions of chapter 17 and 18 have no direct bearing on the rapture positions.

17. The Destruction Of Ecclesiastical Babylon

17:1-2 And there came one of the seven angels which had the seven vials, and talked with me, saying unto me, Come hither; I will shew unto thee the judgment of the great whore that sitteth upon many waters: With whom the kings of the earth have committed fornication, and the inhabitants of the earth have been made drunk with the wine of her fornication.

Chapters 17 and 18 of Revelation are dedicated to the description of the final destruction of Babylon in both its ecclesiastical and political forms. It is evident from these chapters that the events described therein, especially those in chapter 17, precede by some considerable period the events represented in the seven vials. In fact, it is probable that the events of chapter 17 occur at the beginning of the great tribulation. The revelation is given to John, however, subsequent to the revelation of the vials. It must be remembered that from John’s point of view all of the events of the book of Revelation were future, and it pleased God to reveal various aspects of future events in other than their chronological order.

Any interpretation of Revelation 17 and 18 is difficult because expositors have not agreed as to the details of their interpretations. In general, however, it is helpful to consider chapter 17 as dealing with Babylon as an ecclesiastical or spiritual entity and chapter 18 as dealing with Babylon as a political entity. It is also helpful in chapter 17 to distinguish the vision in verses 1 through 6 from the interpretation in verses 7 through 18.

John is shown the vision of the destruction of Babylon, as representing false religion, by one of the seven angels which had the seven vials, and is invited to behold the judgment of a woman, the symbol of Babylon, described as the great whore (Gr., porne, usually translated “harlot”), who is seen sitting on many waters. The interpretation of “waters” is that these are the many nations ruled by Babylon.. The woman is further described as having committed fornication (Gr., porneu, verb form of porn). The inhabitants of the earth are declared to have been made drunk with the wine of her fornication. The picture of the woman as utterly evil signifies spiritual adultery, portraying those who outwardly and religiously seem to be joined to the true God but who are untrue to this relationship. The symbolism of spiritual adultery is not ordinarily used of heathen nations who know not God, but always of people who outwardly carry the name of God while actually worshiping and serving other gods. The concept of spiritual adultery is frequently used in describing the apostasy of Israel (cf. Ezek. 16 and 23; all of Hosea). Characteristically, the Jehovah of the Old Testament is the husband of Israel (cf. Isa. 54:1-8; Jer. 3:14; 31:32). In the New Testament the church is viewed as a virgin destined to be joined to her husband in the future (2 Cor. 11:2), but she is warned against spiritual adultery (James 4:4).

The alliance of the apostate church with the political powers of the world during this future period of time not only debauches the true spiritual character of the church and compromises her testimony in every way but has the devastating effect of inducing religious drunkenness on the part of the inhabitants of the earth. False religion is always the worst enemy of true religion, and the moral wickedness involved in the union of the church with the world imposes a stupefying drunkenness as far as spiritual things are concerned. The hardest to win to Christ and the most difficult to instruct in spiritual truth are those who have previously embraced false religion with its outward show of a worship of God. The concept here presented, enlarging on the previous revelation in 14:8, makes plain that the apostate church has eagerly sought and solicited the adulterous relation with the world political powers and therefore is primarily to be blamed.

17:3-4 So he carried me away in the spirit into the wilderness: and I saw a woman sit upon a scarlet coloured beast, full of names of blasphemy, having seven heads and ten horns. And the woman was arrayed in purple and scarlet colour, and decked with gold and precious stones and pearls, having a golden cup in her hand full of abominations and filthiness of her fornication.

Accepting the invitation of the angel, John is carried away in the spirit, that is, in a spirit of ecstacy, into a place described as the wilderness or literally “wilderness” (no article in the original). From this vantage point John is able to see the woman previously introduced as the great harlot. She is seen seated on a scarlet-colored beast which is full of the names of blasphemy and which has seven heads and ten horns. The scarlet beast is the same one described in 13:1 where the beast is the revived Roman Empire in its character as the center of the world government of Gentile power in that day. The fact that the woman is riding the beast and is not the beast itself signifies that she represents ecclesiastical power as distinct from the beast which is the political power. Her position, that of riding the beast, indicates on the one hand that she is supported by the political power of the beast, and on the other that she is in a dominant role and at least outwardly controls and directs the beast.

The situation here described is apparently prior in time to that described in Revelation 13, where the beast has already assumed all power and has demanded that the world should worship its ruler as God. The situation, therefore, seemingly is in the first half of Daniel’s seventieth week before the time of the great tribulation which is the second half. While such a relationship has many parallels in the past history of the Roman church in relation to political power, the inference is that this is a future situation which will take place in the end time. The significance of the seven heads and the ten horns is revealed subsequently in this chapter, the seven heads apparently referring to forms of government which are successive, and the ten horns to kings who reign simultaneously in the end time. The fact that the woman, representing the apostate church, is in such close association with the beast, which is guilty of utter blasphemy, indicates the depth to which apostasy will ultimately descend. The only form of a world church recognized in the Bible is this apostate world church destined to come into power after the true church has been raptured.
------------
According to the prewrath rapture view, the church will be raptured at an unknown day and hour after the midpoint of the 70th week. Accordingly, the formation and influence of this religious organization will occur BEFORE the rapture ranther than after, as the pretrib position believes.
See study: The Religious Power Base of the Beast
-----------

The description of the woman as arrayed in purple and scarlet and decked with gold, precious stones, and pearls is all too familiar to one acquainted with the trappings of ecclesiastical pomp today and especially of high officials in the Roman Catholic and Greek Orthodox churches. Purple and scarlet, symbolically so rich in their meaning when connected with true spiritual values, are here prostituted to this false religious system and designed to glorify it with religious garb in contrast to the simplicity of pious adornment (cf. 1 Tim. 2:9-10). Alford states, “I do not hesitate therefore…to maintain that interpretation which regards papal and not pagan Rome as pointed out by the harlot of this vision.”²⁷⁸ The most striking aspect of her presentation, however, is that she has a golden cup in her hand described as “full of abomination and filthiness of her fornication.” The Word of God does not spare words in describing the utter filthiness of this adulterous relationship in the sight of God. Few crimes in Scripture are spoken of in more unsparing terms than the crime of spiritual adultery of which this woman is the epitome. As alliance with the world and showy pomp increase, so spiritual truth and purity decline.

17:5 And upon her forehead was a name written, MYSTERY, BABYLON THE GREAT, THE MOTHER OF HARLOTS AND ABOMINATIONS OF THE EARTH.

Upon the forehead of the woman was written her name described as “MYSTERY, BABYLON THE GREAT, THE MOTHER OF HARLOTS AND ABOMINATIONS OF THE EARTH.” The word mystery is a descriptive reference to the title, not a part of the title itself as implied by the capitalization in the Authorized Version. This can be seen by comparing the name given to the woman in 16:19 and 18:2. It has been commonly held that the title “Babylon the Great” assigned to this woman is not a reference to Babylon as a city or to Babylonia as a nation but a religious designation, namely, that the woman corresponds religiously to what Babylon was religiously. The meaning is made clear by her description as “the mother of harlots and abominations of the earth.” It has been noted by many writers that the iniquitous and pagan rites of Babylon crept into the early church and were largely responsible for the corruptions incorporated in Roman Catholicism from which Protestantism separated itself in the Middle Ages.

The subject of Babylon in the Scripture is one of the prominent themes of the Bible beginning in Genesis 10, where the city of Babel is first mentioned, with continued references throughout the Scriptures climaxing here in the book of Revelation. From these various passages, it becomes clear that Babylon in Scripture is the name for a great system of religious error. Babylon is actually a counterfeit or pseudo religion which plagued Israel in the Old Testament as well as the church in the New Testament, and which, subsequent to apostolic days, has had a tremendous influence in moving the church from biblical simplicity to apostate confusion. In keeping with the satanic principle of offering a poor substitute for God’s perfect plan, Babylon is the source of counterfeit religion sometimes in the form of pseudo Christianity, sometimes in the form of pagan religion. Its most confusing form, however, is found in Romanism.

In Genesis 10 and 11 it is recorded that Nimrod was the founder of Babel, later called Babylon. In chapter 11 is recorded the rebellion of men against God in attempting to make a city and a tower that would reach to heaven. The history of the ancient world reveals that it was a common practice to build huge mounds (ziggurats) of sun-dried bricks of which the most ancient illustration has been discovered at Erech, a place mentioned in Genesis 10:10 and dated more than 3,000 years before Christ. The tower of Babel was apparently a forerunner of later towers dedicated to various heathen deities. There was no stone with which to build, and therefore bricks were used with mortar binding them together. The tower of Genesis 11 was a monument to human pride and an express act of rebellion against the true God.

In judging this act God confounded the language of the people and gave the city the name of “Babel,” meaning “confusion” (cf. Gen. 11:9). The city, later named Babylon, had a long history. It became prominent under Hammurabi (1728-1686 B.C.) who was the guiding light to the empire during the Old Babylonian period. Babylon’s greatest glory was achieved under Nebuchadnezzar who lived during the Neo-Babylonian period about 600 years before Christ. Daniel the prophet wrote his book at that time. The story of the city and empire has been deciphered from thousands of cuneiform tablets unearthed by archaeologists.

Of primary importance in the study of Babylon is its relation to religion as unfolded in Revelation 17. In addition to materials given in the Bible itself, ancient accounts indicate that the wife of Nimrod, who founded the city of Babylon, became the head of the so-called Babylonian mysteries which consisted of secret religious rites which were developed as a part of the worship of idols in Babylon. She was known by the name of Semiramis and was a high priestess of the idol worship. According to extrabiblical records which have been preserved, Semiramis gave birth to a son who she claimed was conceived miraculously. This son, given the name of Tammuz, was considered a savior of his people and was, in effect, a false messiah, purported to be the fulfillment of the promise given to Eve. The legend of the mother and child was incorporated into the religious rites and is repeated in various pagan religions. Idols picturing the mother as the queen of heaven with the babe in her arms are found throughout the ancient world, and countless religious rites were introduced supposedly promising cleansing from sin. Though the rites which were observed in the Babylonian false religion differed greatly in various localities, there usually was a priestly order which furthered the worship of the mother and child, practiced the sprinkling of holy water, and established an order of virgins dedicated to religious prostitution. Tammuz, the son, was said to have been killed by a wild beast and afterward brought back to life, obviously a satanic anticipation of the resurrection of Christ.

In the Scriptures themselves, though many of these facts are not mentioned, there are a number of allusions to the conflict of the true faith with this pseudo religion. Ezekiel protests against the ceremony of weeping for Tammuz in Ezekiel 8:14. Jeremiah mentions the heathen practices of making cakes for the queen of heaven (Jer. 7:18) and offering incense to the queen of heaven (Jer. 44:17-19, 25). The worship of Baal, characteristic of pagan religion in Canaan, was another form of this same mystery religion originating in Babylon. Baal is considered identical to Tammuz. The doctrines of the mystery religions of Babylon seem to have permeated the ancient world, giving rise to countless mystery religions, each with its cult and individual beliefs offering a counterfeit religion and a counterfeit god in opposition to the true God revealed in the Scriptures. Babylon as an evil woman is portrayed in the prophecy of Zechariah 5:1-11 where the woman of verse 7 is described as personifying wickedness in verse 8.

The Babylonian cult eventually made its way to other cities including Pergamos, the site of one of the seven churches of Asia. The chief priests of the Babylonian cult wore crowns in the form of the head of a fish, in recognition of Dagon the fish god, with the title “Keeper of the Bridge,” that is, the “bridge” between man and Satan, imprinted on the crowns. The Roman equivalent of the title, Pontifex Maximus, was used by the Caesars and later Roman emperors, and was also adopted as the title for the bishop of Rome. In the early centuries of the church in Rome, incredible confusion arose; and attempts were made to combine some of the features of the mystery religion of Babylon with the Christian faith, a confusion which has continued down to the present day. In this chapter in Revelation, the last stage of counterfeit religion is revealed as it will be in existence in the period before the return of the Lord to earth.

It is a sad commentary on contemporary Christendom that it shows an overweening desire to return to Rome in spite of Rome’s evident apostasy from true biblical Christianity. In fact, modern liberalism has far outdone Rome in its departure from the theology of the early church, thus has little to lose by a return to Romanism. Apostasy, which is seen in its latent form today, will flower in its ultimate form in this future superchurch which will apparently engulf all Christendom in the period after the rapture of the church.

17:6-7 And I saw the woman drunken with the blood of the saints, and with the blood of the martyrs of Jesus: and when I saw her, I wondered with great admiration. And the angel said unto me, Wherefore didst thou marvel? I will tell thee the mystery of the woman, and of the beast that carrieth her, which hath the seven heads and ten horns.

The woman is pictured not only as the source of all evil in apostate Christendom but also as the one who is actively engaged in the persecution of the true saints. Her wickedness in this regard is demonstrated by the description that she is drunken with the blood of the saints and with the blood of the martyrs of Jesus. Here the primary reference is not to ancient Babylon but to Babylon perpetuated in apostate Christendom especially in its future form. The history of the church has demonstrated that apostate Christendom is unsparing in its persecution of those who attempt to maintain a true faith in Jesus Christ. What has been true in the past will be brought to its ultimate in this future time when the martyrs will be beyond number from every kindred, tongue, and nation. The blood shed by the apostate church is exceeded only by that of the martyrs who refuse to worship the beast in the great tribulation. As John contemplates the woman, he records, “I wondered with great admiration,” or more literally, “I wondered with great wonder” (the verb in the Greek, thaumazo, has the same root as the noun thauma, both meaning “to regard with wonder or astonishment”).

The angel, perceiving that John wonders at what he sees, states that he will declare the mystery of the woman and of the beast. He does so, however, by describing the beast first in detail, then the woman and subsequent action relating to her. Few passages in Revelation have been the subject of more dispute among scholars who have attempted to interpret them than this explanation of the angel. Great care, therefore, must be exercised in determining precisely the component parts of the divine revelation herein given.

17:8 The beast that thou sawest was, and is not; and shall ascend out of the bottomless pit, and go into perdition: and they that dwell on the earth shall wonder, whose names were not written in the book of life from the foundation of the world, when they behold the beast that was, and is not, and yet is.

The angel first gives a detailed description of the beast in his general character. The beast is explained chronologically as that which was, is not, and is about to ascend from the abyss and go into perdition. “The bottomless pit” (Gr., abyssos, meaning “bottomless,” or “the abyss”) is the home of Satan and demons and indicates that the power of the political empire is satanic in its origin as is plainly stated in 13:4.

(I disagree that the abyss is THE HOME of Satan. Satan does not have "a home" other than the earth, which he is ruler over and god of [2 Cor. 4:4; John 12:31] SEE Topic: Satan: rulership)

 The word perdition (Gr., apoleia) means “destruction” or “utter destruction,” referring to eternal damnation. The power of the political empire in the last days is going to cause wonder as indicated in the questions in 13:4: “Who is like unto the beast? who is able to make war with him?” The overwhelming satanic power of the final political empire of the world will be most convincing to great masses of mankind.

There is a confusing similarity between the descriptions afforded Satan who was apparently described as the king over the demons in the abyss (9:11), “the beast that ascendeth out of the bottomless pit” (11:7), the beast whose “deadly wound was healed” (13:3), and the beast of 17:8. The solution to this intricate problem is that there is an identification to some extent of Satan with the future world ruler and identification of the world ruler with his world government. Each of the three entities is described as a beast. Only Satan himself actually comes from the abyss. The world government which he promotes is entirely satanic in its power and to this extent is identified with Satan. It is the beast as the world government which is revived. The man who is the world ruler, however, has power and great authority given to him by Satan. The fact that Satan and the world ruler are referred to in such similar terms indicates their close relationship one to the other.

While many have attempted to demonstrate from this verse that the final world ruler is some resurrected being such as Judas Iscariot,²⁷⁹ Nero,²⁸⁰ or one of the more recent world rulers, it would seem preferable to regard the “eighth” beast as the political power of the world government rather than its human ruler. What is revived is imperial government, not an imperial ruler (cf. Rev. 13:3). That which seemingly went out of existence in history never to be revived is thus miraculously resuscitated at the end of the age.
-------------
(I believe that the fatal wound is actually on the benevolent ruler who will then be brought back to life by Satan, and through Satan's power become the beast.
There are several views on this wound as well as the healing, and all I can do is line up with one of them and give my reasons and then let the reader pursue it from there. But it should be clear that the wound and its healing take place in connection with the mid-point of the 70th week. And as a result of the healing, the people will be influenced to follow the beast. Therefore, it is probable that the wound takes place shortly before the mid-point and the healing takes place at or shortly after the midpoint in order to correlate with the Satanic empowering and the fantastic impact on the people. With this in view, the popular idea that the wound is the fall of the Roman Empire and the healing is the restoration of that type of government in the form of the 10 nation confederacy is not adequate.
Details of my position are in the study:
The Midpoint of the Week.)
------------------

17:9-11 And here is the mind which hath wisdom. The seven heads are seven mountains, on which the woman sitteth. And there are seven kings: five are fallen, and one is, and the other is not yet come; and when he cometh, he must continue a short space. And the beast that was, and is not, even he is the eighth, and is of the seven, and goeth into perdition.

The explanation of the beast introduced by the unusual phrase “here is the mind which hath wisdom” anticipates the difficulty and complexity of the revelation to follow. The reader is warned that spiritual wisdom is required to understand that which is unfolded. The first key to the revelation is in the statement “The seven heads are seven mountains on which the woman sitteth.” Many expositors refer this to Rome. Seven hills formed the nucleus of the ancient city on the left bank of the Tiber. These hills received the names of Palatine, Aventine, Caelian, Esquiline, Viminal, Quirinal, and Capitoline.²⁸¹ As Rome grew, however, the hill Janiculum on the other side of the river Tiber was often included among the seven, as Alford does, omitting the Capitoline.²⁸² Later the hill Pincian to the north of the ancient city was also included in the hills of Rome as the city developed and moved north.²⁸³ This passage in Revelation is taken, therefore, to indicate that the seat of the ecclesiastical power will be in Rome geographically rather than in Babylon. Throughout its history Rome has been described as the city of seven hills as indicated in coins which refer to it in this way and in countless allusions in Roman literature. Victorinus, one of the first to write a commentary on the book of Revelation, identified the seven mountains as the city of Rome.²⁸⁴

The seven heads of the beast, however, are said to be symbolic of seven kings described in verse 10. Five of these are said to have fallen, one is in contemporary existence, that is, in John’s lifetime, the seventh is yet to come and will be followed by another described as the eighth, which is the beast itself. In the Greek there is no word for “there,” thus translated literally, the phrase is “and are seven kings.” The seven heads are best explained as referring to seven kings who represent seven successive forms of the kingdom. Because the seven heads are identified with kings in verse 10, some prefer to divorce the meaning from the city of Rome entirely and center the ultimate fulfillment in a rebuilt Babylon on the site of ancient Babylon.

Seiss marshals a convincing array of evidence that the seven mountains of 17:9 refer not to the seven hills of Rome but rather to successive imperial governments. An extensive quotation of Seiss on this important point is necessary to present the matter fully:

John further saw this Woman sitting upon a scarlet Beast, full of names of blasphemy, having seven heads and ten horns. This Beast is the same described in chapter 13. He is referred to here, not so much to make us better acquainted with him, as to give us a full understanding of the Great Harlot and her relationships. The “wisdom” or inner sense and meaning of the presentation is, that “the seven heads are seven mountains, where the Woman sitteth upon them, and are seven kings.” These are the words which are supposed to fix the application of the picture to the city of Rome, as Rome is called a city of seven hills. But a flimsier basis for such a controlling and all-conditioning conclusion is perhaps nowhere to be found. The seven hills of the city of Rome, to begin with, are not mountains, as every one who has been there can testify; and if they were, they are more characteristic of the situation of Rome than the seven hills are characteristic of Jerusalem. But the taking of them as literal hills or mountains at all is founded upon a total misreading of the angel’s words.

A mountain, or prominent elevation on the surface of the earth, is one of the common scriptural images, or representatives of a kingdom, regal dominion, empire, or established authority. So David, speaking of the vicissitudes which he experienced as the king of Israel, says: “Lord, by Thy favour Thou didst make my mountain to stand strong” —margin, “settled strength for my mountain,” meaning his kingdom and dominion. (Ps. 30:7.) So the Lord in His threat against the throne and power of Babylon said: “I am against thee, O destroying mountain, which destroyest all the earth; and I will stretch out mine hand upon thee, and will roll thee down from the rocks, and will make thee a burnt mountain.” (Jer. 51:25.) So the kingdom of the Messiah is likened to “a stone, which became a great mountain, and filled the whole earth.” (Dan. 2:35.) And this is exactly the sense in which the angel uses the word here, as he himself tells us. He does not say, “the seven heads are seven mountains, where the Woman sitteth upon them,” and there leave off; but he adds immediately, “and they are seven kings,” or personified kingdoms. The mountains, then, are not piles of material rocks and earth at all, but royal or imperial powers, declared to be such by the angel himself. The description, therefore, so far from fixing the application to the Papacy, or to the city of Rome, decisively settles that it cannot possibly apply to either, for neither has seven such mountains. The late Albert Barnes has written in his Notes that “all respectable interpreters agree that it refers to Rome; either Pagan, Christian, or Papal.” Of course he is one of the “respectable interpreters,” but then he should be able to tell which of the objects he names it is, for it cannot be all three. Most people assign Dr. E. W. Hengstenberg, the great Berlin professor, a place among “respectable interpreters,” but Hengstenberg says Rome cannot possibly be meant by these seven heads. The angel says they are seven regal mountains, seven kings, seven great ruling powers. Rome Papal cannot be meant, for Rome Papal has no such count of seven regal powers. Rome Christian cannot be meant, for Rome Christian, as distinguished from Rome Papal, never supported and carried the great Harlot in any possible sense, and could not without ceasing to be Christian. Rome Pagan cannot be meant, for Rome Pagan ceased with the conversion of the throne, and no count of emperors or kings can be found in it to “respectably” fill out the angel’s description. The succession of the forms of administration, enumerated as Kings, Consuls, Dictators, Decemvirs, Military Tribunes, and Emperors, were not seven kings or regal mountains. Prior to the empire most of these administrations were less than anthills in the history of the world, and furnished rather slender ponies for the great purple-clad and pearl-decked mother of harlots to ride on in her majesty. Rome surely comes into the count of these seven mountains of empire; but to make Rome the whole seven, including also the eighth, requires a good deal more “respectability” of interpretation in that line than has thus far appeared. Barnes is sure the whole thing applies to Rome because this Woman “hath rule or kingdom upon the kings of the earth, and there was no other empire on the earth to which this could be properly applied.” But this assumes that the Woman is an empire, for which there is not a particle of evidence. The Woman is not an empire any more than the Church of Christ is an empire. She rides upon empires, kings, and powers of the world, and inspires, leads, and controls them; but she herself is not one of them, and is above all of them so that they court her, and are bewitched and governed by her— governed, not with the reins of empire, but with the lure of her fornication. This Woman is longer-lived than any one empire. We have seen that she bears the name of Babylon, and is not destroyed until the day of judgment. The seven imperial mountains on which she rides must therefore fill up the whole interval; or there was a time, and the most of her history, when she did not ride at all, which is not the fact. Seven is itself the number of fulness, which includes the whole of its kind. The reference here is to kings, to mountains of temporal dominion, to empires. It must therefore take in all of them. And when men once get over their “respectability,” and rise to the height of range of the interpreting angel’s view of things, they will have no difficulty in identifying the mountains, or the times to which they belong.

Of these seven regal mountains, John was told “the five are fatten,” dead, passed away, their day over; “the one is,” that is, was standing, at that moment, was then in sway and power; “the other is not yet come, and when he shall come, he must continue a little time.” What regal mountain, then, was in power at the time John wrote? There can be no question on that point; it was the Roman empire. Thus, then, we ascertain and identify the sixth in the list, which shows what sort of kings the angel meant. Of the same class with this, and belonging to the same category, there are five others—five which had then already run their course and passed away. But what five imperial mountains like Rome had been and gone, up to that time? Is history so obscure as not to tell us with unmistakable certainty? Preceding Rome the world had but five great names or nationalities answering to imperial Rome, and those scarce a schoolboy ought to miss. They are Greece, Persia, Babylon, Assyria, and Egypt; no more, and no less. And these all were imperial powers like Rome. Here, then, are six of these regal mountains; the seventh is not yet come. When it comes it is to endure but a short time. This implies that each of the others continues a long time; and so, again, could not mean the dictators, decemvirs, and military tribunes of the early history of Rome, for some of them lasted but a year or two. Thus, then, by the clearest, most direct, and most natural signification of the words of the record, we are brought to the identification of these seven mountain kings as the seven great world-powers, which stretch from the beginning of our present world to the end of it. Daniel makes the number less; but he started with his own times, and looked only down the stream. Here the account looks backward as well as forward. That which is first in Daniel is the third here, and that which is the sixth here is the fourth in Daniel. Only in the commencing point is there any difference. The visions of Daniel and the visions of John are from the same Divine Mind, and they perfectly harmonize, only that the latest are the amplest.

By these seven great powers then, filling up the whole interval of this world’s history, this great Harlot is said to be carried. On these she rides, according to the vision. It is not upon one alone, nor upon any particular number of them, but upon all of them, the whole seven-headed Beast, that she sits. These seven powers, each and all, support the Woman as their joy and pride; and she accepts and uses them, and sways their administrations, and rides in glory by means of them. They are her devotees, lovers, and most humble servants; and she is their patronizing and most noble lady, with a mutuality of favours and inter-communion belonging to her designation. This is the picture as explained by the angel. But, to say that the Romish Papacy was thus carried, nurtured, and sustained by the ancient empires of Greece, Persia, Babylon, Assyria, and Egypt, would be a great lie on history. It was not so. In the nature of things it could not be so. By no means then can this Harlot be the Papacy alone, as maintained by all “respectable interpreters.” Furthermore, it is a matter of fact, that as surely as Rome in John’s day, and Greece, Persia, Babylon, Assyria, and Egypt, before Rome, existed and bore sway on earth as regal mountains, so surely and conspicuously were they each and all ridden by this great Harlot. They were each and all the lovers, supporters, and defenders of organized falsehood in religion, the patrons of idolatry, the foster friends of all manner of spiritual harlotry. Nimrod, the hunter of the sons of men and author of despotic government, established his idolatrous inventions as the crown and dory of his empire, and intertwined the worship of idols with the standards of his power. It was the same with Egypt, whose colossal remains, unfading paintings, and mummy scrolls confirm the Scripture portraitures of her disgusting devotions, and tell how the priests of these abominations were honoured by the throne, of which they were the chief advisers. It was so with Assyria, as the recent exhumations of Nineveh abundantly attest. It was so with the Babylon of Nebuchadnezzar, as Daniel, who lived amid it all, has written. It was so with Persia, as her various records all declare. It was so with Greece, as her own most cherished poets sung, her mightiest orators proclaimed, and all her venerated artists and historians have set forth. It was so with Rome, as all her widespread monuments still show, and all the Christian testimonies, with her own, render clear and manifest as the sun. And it will be so with the last, which is yet to come, as declared in the apocalyptic foreshowings, and in all the prophecies in the Book of God upon the subject. It requires but a glance at history to see that spiritual harlotry has ever been the particular pet and delight of all the Beast-powers of time. If ever the worship and requirements of the true God won their respect and patronage, they soon corrupted it to their own selfish and ambitious ends, or never were easy until freed from the felt restraint.²⁸⁵

The final form of world government, symbolized by the eighth beast itself, is the world empire of the great tribulation time. The revived Roman Empire which will be in sway immediately after the rapture of the church is apparently indicated by the seventh head, while the beast, described in verse 11 as the eighth, is the world empire, which is destroyed by Jesus Christ at His second coming. In summation, what is described in verses 8 through 11 is the final form of Gentile world power in alliance with apostate religion symbolized by the harlot.
-----------
Again, this "seventh" kingdom comes into existence BEFORE the rapture and probably prior to  the start of the 70th week.
The influence then, of the Roman Empire, will continue to be felt throughout subsequent history and finally reach a stage in the last days where it is to be viewed as a 10 nation confederacy which will once again have a world-wide impact. And yet, this confederacy is not to be viewed as a kingdom "power" on the earth, but rather a political body or organization which works for the mutual benefit of the whole world. Since this organization will not have "authority" itself, it is probable that its influence will be carried out in a "behind the scenes" manner until such time as it is taken over by the world ruler.
The beast himself is the "eighth" who will destroyed during the Armageddon campaign.
For more details see study: The Political Power Base of the Beast
---------------------

17:12-14 And the ten horns which thou sawest are ten kings, which have received no kingdom as yet; but receive power as kings one hour with the beast. These have one mind, and shall give their power and strength unto the beast. These shall make war with the Lamb, and the Lamb shall overcome them: for he is Lord of lords, and King of kings: and they that are with him are called, and chosen, and faithful.

Further detail is given concerning the final stage of the world empire as having a nucleus of ten kings apparently joined in a confederacy represented by the ten horns. These kings in contrast to the seven heads of the beast are kings who rule not in succession but simultaneously at the end time. By comparison with chapter 13, it will be seen that this is the form of the Roman Empire just preceding the world empire. The ten horns’ rule as kings is subject to that of the beast itself, and their sphere of power is brief. They are a phase of the transmission of power from the various kingdoms to that of the beast itself. This is shown by verse 13 where it is said that these have one mind and shall give their power and strength to the beast. They are further described as making war with the Lamb, a reference to the Lord Jesus Christ, and their ultimate subjugation under the Lamb is destined to be fulfilled at the second coming. A brief anticipation of this triumph is indicated in verse 14 where the Lamb is prophesied to overcome them as Lord of lords and King of kings. Those on the side of the Lamb are called, chosen and faithful.

17:15 And he saith unto me, The waters which thou sawest, where the whore sitteth, are peoples, and multitudes, and nations, and tongues.

In the first verse of the chapter the harlot is seen sitting upon many waters. Here the description and the symbolic meaning of the waters are given as referring to people, multitudes, nations, and tongues. Generally speaking, when water is mentioned in Revelation, it should be taken literally. The fact that a symbolic meaning is specifically assigned to it here indicates that this is the exception to the usual rule. The situation described here is one of great political power on the part of the beast but a sharing of rule with the woman who controls the multitudes of the world.

17:16-18 And the ten horns which thou sawest upon the beast, these shall hate the whore, and shall make her desolate and naked, and shall eat her flesh, and bum her with fire. For God hath put in their hearts to fulfil his will, and to agree, and give their kingdom unto the beast, until the words of God shall be fulfilled. And the woman which thou sawest is that great city, which reigneth over the kings of this earth.

Verse 16 reveals a most remarkable development in the vision which is also the climax and the purpose of the preceding description. Here the ten horns, previously seen as ten kings, destroy the woman riding the beast in a most graphic action. The best reading indicates that both the ten horns and the beast combine in this effort. The expression “upon the beast” is most accurately translated according to the better manuscripts “and the beast.” The action of this verse is cast in the future tense which must be understood as future from John’s point of view. The destruction of the harlot reduces all her pomp and gorgeous robes to naught. She is stripped of them, her flesh is eaten, and she is burned with fire. These graphic words clearly picture the downfall of the apostate world church of the future.

By comparison with other scriptures, the time of the event may be placed approximately at the midpoint of the seven years of Daniel’s seventieth week, which leads up to and climaxes in the second coming of Christ. During the first half of the seven years, apostate Christendom flowers and establishes its power over all the world. During this period there is a measure of religious freedom as indicated by the fact that the Jews are allowed to worship and renew their sacrifices (Dan. 9:27). There may be widespread preaching of the gospel in this same period, as it would hardly seem possible to extend religious freedom to the Jews without doing the same for all. However, the triumph of the ecumenical movement is simultaneous with this final effort. All religions of the world, apart from the true faith in Christ, gather in one great world church. Only those who are truly saved, whose names are written in the Lamb’s book of life and who know Jesus Christ as Saviour and Lord, seem to escape this movement toward unification. The climax of this series of events is seen in the early portion of chapter 17 where the woman in all her pomp and wickedness is riding the beast.

However, with the beginning of the second half of the week, the ruler of the revived Roman Empire, who is the political head of the world empire and is himself designated also as “the beast,” is able to proclaim himself dictator of the whole world. In this capacity he no longer needs the help and power of the church. He therefore destroys the world church and substitutes for this ecclesiastical apostasy the final form of wickedness in the area of religion, the worship of himself. According to 13:8, all men shall worship the beast except true believers in Christ. Many find a parallel revelation in Daniel 11:36-39 where the willful king likewise puts aside all other deities in favor of the worship of himself.

The divine judgment inflicted upon apostate Christendom follows a pattern which can be observed in other judgments upon wicked nations and ungodly rulers. Ancient Babylon was used to bring affliction upon the people of Israel, as were also the governments of Assyria and Egypt. But in due time the same nations who inflicted divine judgment were themselves the objects of God’s wrath. The principle involved is plainly stated in verse 17. Their action, though inspired by a blasphemous attempt to institute a world religion utterly contrary to divine revelation, nevertheless fulfills God’s will that the kingdoms of the world should come under the domain of the beast in fulfillment of prophecy until the end of the age, indicated in the phrase “until the words of God shall be fulfilled.” Thus the plan of the ages unfolds majestically, and Scripture indicates that God sovereignly permits the increment of wickedness until the cup of iniquity overflows.

At the close of the chapter, the woman is again identified with the great city which reigned over the kings of the earth, referring to the ecclesiastical power and control of the political which characterized portions of church history in the past and will have its climax in this future period. The “great city” is obviously a reference to Babylon in its religious rather than its historical significance. The influence of Babylon on Roman Christianity was partly responsible for the assumption by Rome of political power, namely, the authority of the church over the state. Just as ancient Babylon conquered kings in a political way, so its religious counterpart would dominate political states during the period of Roman papal power.

The interpretation that this is a reference to pagan political Rome as advanced by the historical school of interpretation or that it refers to a future literal city of Babylon is wrong. The city here according to verse 5 is a mystery, not a literal city. The entire context of chapter 17 supports this interpretation, distinguishing as it does between the city identified with the woman and the political power referred to as the beast and the ten horns.²⁸⁶

After the disposal of Babylon in its religious form by its destruction at the hands of the beast, the prophetic revelation in chapter 18 then deals with Babylon as a political force also destined for destruction at a later date.

²⁷⁸ Henry Alford, The Greek New Testament, IV, 705.

²⁷⁹ Cf. Kenneth Wuest, Prophetic Light in Present Darkness, pp. 67-70.

²⁸⁰ H. H. Rowley, The Relevance of the Apocalyptic, pp. 130, 132.

²⁸¹ William Smith, Dictionary of Greek and Roman Geography, II, 719-21.

²⁸² Alford, IV, 710.

²⁸³ Smith, ibid.

²⁸⁴ Cf. J. B. Smith, A Revelation of Jesus Christ, p. 245.

²⁸⁵ Joseph A. Seiss, The Apocalypse, pp. 391-94.

²⁸⁶ Cf. Alford, IV, 711-12.