Why is Rome referred to as Babylon in Rev 17 and 18?

The preponderance of the evidence appears to show that in the New Testament, "Babylon" is a reference to Rome.

John AT Robinson provided a helpful summary of supporting evidence (see p. 136 here):

The 'greetings from her who dwells in Babylon, chosen by God like you' (5.13) is almost universally agreed to be a disguise for the church in Rome. The pseudonym is indisputable in the book of Revelation (14.8; 16.19; 17.5; 18.2, 10, 21) as it is in other late-Jewish and Christian writings (II Bar.10.1f; 11.1; 67.7; II Esd.3.1f., 28, 31; Orac. Sib.5. 143, 159f.), and it was so understood here as early as Papias. [Eusebius, HE 2.15.]

This includes not only Papias, who was acquainted with 1st generation Christians, but also shows the wealth of Jewish literature supporting the conclusion.

That "Babylon" was a type or symbol for wickedness, wicked people, or wicked places has a long history in Jewish writings. See, for example, Isaiah 14, which compares the king of Babylon to Lucifer himself.

We have 1st & 2nd century sources that indicate that Peter, Mark, and John spent time in Rome (e.g. 1 Clement for Peter, Pauline epistles for Mark, Tertullian for John). We have no such evidence that they were ever in Babylon.

Christian use of Babylon to describe a wicked place is influenced heavily by Isaiah, even if the Babylon-wickedness theme is not present throughout the Old Testament.

Prophecies in Daniel cover some of the same events as those in Revelation. These prophecies normally refer to kingdoms as beasts of various kinds. The prophecies are centered on Israel, so all these beasts are empires that will conquer Jerusalem for a time. In Daniel's prophecy (Daniel 2), Babylon is the head of Gold and is a synedoche for all the kingdoms that would conquer Jerusalem and Israel. Since Rome is one of those empires, Babylon is prophetically its head.

Revelation also speaks of eight empires:

Rev 17:9-11: “This calls for a mind with wisdom. The seven heads are seven hills on which the woman sits. They are also seven kings. Five have fallen, one is, the other has not yet come; but when he does come, he must remain for only a little while. The beast who once was, and now is not, is an eighth king. He belongs to the seven and is going to his destruction.

What are the five empires that have fallen?

1. Israel
2. Assyria
3. Babylon
4. Medo-Persia
5. Greece

Rome is the sixth empire, the one that still exists in John's time. The next empire to conquer the Holy Land was Islam, making it the seventh empire. The eight and final empire will be assembled from some of the pieces of the preceding seven empires, which is why it is called the "leopard-bear-lion":

Rev 13:2: The beast I saw resembled a leopard, but had feet like those of a bear and a mouth like that of a lion. The dragon gave the beast his power and his throne and great authority.

The leopard is Greece (part of whose ancient empire is occupied by present day Turkey), the bear is Medo-Persia (Iran and the Kurdish people), and the lion is Babylon (Iraq), so it is possible that some collection of middle eastern countries will form a new empire, but that does not rule out the inclusion of some parts of Europe.

Why is Rome referred to as Babylon in Revelation chapters 17 and 18?

If people think Rome is Babylon then I suggest that some people look up which nation is called Babylon the most in the Bible. It is quite an eye opener indeed.

Basically, it comes to pointing out that Rome in built on seven (7) hills. But this just one interpretation.

6 I saw that the woman was drunk with the blood of God’s holy people, 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 yet will come up out of the Abyss and go to its 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 it 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. 10 They are also seven kings. Five have fallen, one is, the other has not yet come; but when he does come, he must remain for only a little while. 11 The beast who once was, and now is not, is an eighth king. He belongs to the seven and is going to his destruction. - Revelation 17:6-11

The problem with prophecies in general is that it is almost impossible to know the correct interpretation(s) to them until the actual time of fulfillment is upon us. Thus, The Prophecies of the Popes is no exception.

The original Greek text of this particular prophecy does not name the city of Rome as being the city of seven hills. Its interpretation as to which city is the actual one is still an open question.

Nevertheless it is almost safe to believe that it may be one of the three following seven-hilled cities: Rome, Constantinople (Istanbul) or Jerusalem. Given the very eschatological nature of this prophecy, Jerusalem could very well be the city in question.

This question focuses on Rome, but I simply suggested other possibilities as well. Besides, did not Jerusalem see the the killing of many Prophets and Our Lord Jesus Christ.

Jerusalem's seven hills are Mount Scopus, Mount Olivet (Mount of Olives) and the Mount of Corruption (all three are peaks in a mountain ridge that lies east of the old city), Mount Ophel, the original Mount Zion, the New Mount Zion and the hill on which the Antonia Fortress was built.

It was common custom, years before the New Testament, for people in the Roman world to refer to Rome itself as the "city of seven hills." Tradition states that when Romulus and Remus, who founded Rome, wanted to build a city in the area of the Tibur (Tiber) River, they specially chose a site that had this unique characteristic. The city of Jerusalem, as it existed in Jesus' time, was also reckoned a "city of seven hills."

Jerusalem is not the only city in the world considered or historically believed to be built on seven hills. Others include Babylon, Moscow, Mecca, Lisbon, Tehran and Amman.

Jerusalem's Seven Hills

For those interested here are the maps of the three “seven-hilled” cities.

Rome

Constantinople: The seven hills of Istanbul

Jerusalem and its Seven Hills

What did Christ mean when He said in Luke 13:33: “… it cannot be that a prophet should perish outside of Jerusalem.”?