“What cities have 7 hills? Rio, Rome, and... Jerusalem. Every Jewish school child learns the names of the 7 hills of Jerusalem.”
Many cities are built on 7 hills:
https://en.wikipedia.org/wiki/List_of_cities_claimed_to_be_built_on_seven_hills
One not on the list is Neom, Saudi Arabia:
https://en.wikipedia.org/wiki/Neom
According to one blogger (https://nightwatchman.blog/2018/09/18/7-kings-and-7-mountains-of-neom-saudi-arabia/ NOT AN ENDORSEMENT) it is being built on 7 mountains: Jabal Al-Lawz, Jabal Al Qalom, Jabal Maqla, Jabal Ad-Dubbagh, Jabal Harb, Jabal Huwad, and Jabal Shar.
The city is meant to be a city for the whole world and plans to use ocean shipping, among other commerce, as a means to generate wealth.
In Revelation Babylon seems to be both a political and religious system embodied in a specific city. Traditionally, Rome has been the most popular city designated as being symbolized by Babylon. However, many have also said that Babylon will be rebuilt.
Every generation of Christian tends to see prophetic fulfillment in the current events. If we lived in WW2 we certainly would have thought it was the end. Perhaps it is very close, but we cannot know until it actually arrives.
Attempts to identify Babylon, antichrist, and the mark of the beast are very speculative in my opinion. That’s not necessarily bad; we just shouldn’t be too dogmatic about something that the Bible has not made altogether clear.
Yes, many cities are built on seven hills, but only one city in the world fits the other criteria in the description of “Mystery Babylon”, and it isn’t in Saudi Arabia.