Throughout this summer I've been honored to preach through the book of Revelation. As I've shared before, I am of the conviction through study, and prayer that the contents of the book of Revelation was originally given as a vision by Jesus (1:1), to the Apostle John (1:1), for the immediate benefit (blessing 1:3) of seven historic first-century churches (1:11) in what we would today call western Turkey, what was called in the Roman Empire "Asia". 

As John received this vision he wrote it down on a scroll (1:9-11). The details of the vision tell of both specific instructions to each of the local seven historic churches (chapters 2-3), along with many scenes of what was yet to come regarding the destruction of Jerusalem, the passing away of the "old order" of things (IE Temple sacrificial worship), the establishment of the "new order" of things via worship done in spirit and in truth (Christian worship focused on Christ's life, death, resurrection, ascension, and reign) and the victorious, everlasting rule of Jesus.

Since so much of Revelation has to do with the (then pending) destruction and judgment of the "old order" of things (IE Temple sacrificial worship) it should come as no surprise that the headquarters location of the "old order" is the focus of much of Revelation. Jerusalem is referenced often throughout the book of Revelation and given many apocalyptic nicknames. 

Jerusalem is referenced by way of proximity in Revelation 11:1-2:

1 I was given a reed like a measuring rod and was told, “Go and measure the temple of God and the altar, with its worshipers. 2 But exclude the outer court; do not measure it, because it has been given to the Gentiles. They will trample on the holy city for 42 months.

The Temple at the time of the first century (prior to 70 A.D.) was located in Jerusalem. To reference the temple, either via a symbolic or spiritual reference or as a physical reference is still certainly a reference that calls to mind the host city where the physical temple resided. Verse 2 goes on to say that the holy city will be trampled for 42 months. This is a similar time frame to the total duration of the First Jewish War which lasted from 66-70 A.D. 

Jerusalem is again referenced later in chapter 11 in verse 8:

8 Their bodies will lie in the public square of the great city—which is figuratively called Sodom and Egypt—where also their Lord was crucified.

There are two clues here to consider regarding this "great city". Firstly, the last city which was referenced was Jerusalem (in 11:1-2). Therefore in this sentence, there are no other referents for this city. Grammatically we would have to perform Greek circus tricks to try and twist this reference to another location other than Jerusalem. Secondly, the text provides us with a detail that solidifies the location being referenced in the vision. The location is the same place where "where also their Lord was crucified" (ὅπου καὶ ὁ κύριος αὐτῶν ἐσταυρώθη). All four gospels & the book of Acts refer to Jerusalem as being the location where Christ was crucified. 

Jerusalem is again the referent in chapter 11 in verse 13: 

13 At that very hour there was a severe earthquake and a tenth of the city collapsed. Seven thousand people were killed in the earthquake, and the survivors were terrified and gave glory to the God of heaven.

A description is given of the city in the midst of a tremendous earthquake. I'll note here that I've previously commented on a reference of earthquake in Revelation 8 and you can read more via the link. When earthquakes are mentioned in the Old Testament, they are often descriptions of geopolitical shifts in accompaniment to God's judgment. Jerusalem certainly suffered judgment in 70 A.D. and underwent a massive geopolitical shift in losing the Jewish war of rebellion against Rome. 

Jerusalem seems to go unreferenced for a few scenes and the next time it comes up as the focus is in 14:8:

8 A second angel followed and said, “ ‘Fallen! Fallen is Babylon the Great,’ which made all the nations drink the maddening wine of her adulteries.”

We may ask, how is Jerusalem being referenced since the city is called "Babylon the Great"? The answer to this is simple enough. Either we must interpret this reference to a new location (previously unmentioned), or a previous reference earlier in the text. The last reference to a city was in 11:13, which we already know is the same city from 11:8 - the city where the Lord was crucified: Jerusalem. If this is not a reference to the previous city (Jerusalem) and is a new city, we would expect it to have clear reference later in the text. 

The city is again in mind in 14:20: 

20 They were trampled in the winepress outside the city, and blood flowed out of the press, rising as high as the horses’ bridles for a distance of 1,600 stadia

There is no other city as a candidate for this city by way of reference. This city is the same city as what was mentioned in 14:8. The distance measured (1,600 stadia) is of significance because it represents an area of land slightly larger than the size of biblical Israel. The scene that is described here is where the winepress is outside the city (Jerusalem) and the destruction overflows over the cities borders. This can be understood as a prophetic description of the bloodshed during the Jewish revolt of 66-70 A.D. and how far-reaching the devastation and death from that war. 

The next time a city is referenced is in Revelation 17:5 and again (like in 14:8) the reference is to Babylon, this time with a more clear explanation in 17:18.

The name written on her forehead was a mystery: 

BABYLON THE GREAT 

THE MOTHER OF PROSTITUTES 

AND OF THE ABOMINATIONS OF THE EARTH. (Rev 17:5)

In this chapter there is a relationship described between the Beast and a Harlot (17:3). The Beast and Harlot are two independent entities who enter into a relationship together. They both have overlapping agendas (for a time) and both enjoy the byproducts of their shared relationship (for a time). The Harlot throughout the chapter is a city as we come to find out in 17:18:

18 The woman you saw is the great city that rules over the kings of the earth.” (Rev 17:18)

It's always nice when God's Word gives us explicit instructions on interpreting it! Let's recap what we have so far:

• We know that Jerusalem is in mind as the "holy city" (11:1-2). 
• We know that Jerusalem takes on the nicknames "Sodom" and "Egypt" (11:8). 
• We know that Jerusalem is the subject of great upheaval (11:13).
• We aren't sure yet, but have a possibility that Jerusalem is also being given the nickname "Babylon" (14:8 & 17:5, 17:18)

"But even pagan writers speak highly of Jerusalem as a significant contemporary city. Tacitus calls it “a famous city.” Pliny the Elder comments that it is “by far the most famous city of the ancient Orient.” Appian, a Roman lawyer and writer (ca. AD 160) called it “the great city Jerusalem” (Tacitus, Histories 5:2; Fragments of the Histories 1; Pliny, Natural History 5:14:70; Appian, The Syrian Wars 50). The Sibylline Oracles, Josephus, and the Talmud concur in calling Jerusalem “a great city” (Sibylline Oracles 5:150–154, 408–413; Josephus, J.W. 7:1:1; 7:8:7." ( Click here to read full article)

• The Harlot is described as "drunk with the blood of God's holy people" (17:6). Take a look at this list of instances where Jerusalem is seen as the primary driving force persecuting God's New Testament people: Acts 4:3; 5:18–33; 6:12; 7:54–60; 8:1ff; 9:1–4, 13, 23; 11:19; 12:1–3; 13:45–50; 14:2–5, 19; 16:23; 17:5–13; 18:12; 20:3, 19; 21:11, 27; 22:30; 23:12, 20, 27, 30; 24:5–9; 25:2–15; 25:24; 26:21. See also: 2 Co 11:24; 2Th 2:14–15; Heb 10:32–34. (Click here for source of list)
• The Harlot is described as riding on the Beast with seven heads and ten horns (17:7). A few verses later the Beast is further described (17:9) and explained: "The seven heads are seven hills on which the woman sits". Rome was most famously the city of seven hills in the ancient world. This nickname is akin to our modern nicknames for New York City as the "big apple" or for St. Louis as the "Gateway to the West". Jerusalem was supported by Roman Imperial authority (until the Jewish revolt began in 66 A.D. and ended with the destruction of Jerusalem in 70 A.D.). 
• The Harlot and the Beast eventually turn on each other (17:15-16). Until the Jewish revolt, Jerusalem had a special political relationship with Rome in that the Jews were allowed to continue their religious worship in Jerusalem provided that they (like other conquered peoples) paid homage, and taxes to Caesar. 
• The Harlot is eventually identified with the same language as Jerusalem from 11:8, 14:8, and 17:5. The great city is Jerusalem, the Harlot and Jerusalem are one and the same. The Harlot is therefore a symbolic, prophetic nickname given to what Jerusalem has become. Rather than remaining faithful to the Lord God, Jerusalem has rejected the Son of God and instead furthered it's heinous rebellion.