The New Jerusalem from Heaven to Earth

The usual habit of Roman Catholicism, ORthodoxy and
protestantism is to treat this as figurative and symbolic and
spiritualize it. no specific explanation given.

But this is after the new heavens and new earth the restoration of
the earth to its original condition, after the Second Coming of
Jesus Christ to judge the living and the dead and rule on earth
"and of His kingdom there shall be no end" says the Nicene-
Constantinopolitan Creed.

Chiliasm that was rejected was the idea that Christ's reign would
only last 1,000 years, not that it wouldn't be physical. The first
to denounce physicality of the Kingdom of Heaven was a pupil
of Origen who considered it all just too disgustingly material and
physical icky material stuff.

Origen was subclinically gnostic, and started his drift to absurdities
a laundry list he was eventually anathematized for post mortem,
because he was always looking for some deeper hidden meaning
in Scripture.

Orthodoxy admits the literal meaning and that there can be other
applications.

Thanks to Augustine (origin of a lot of problems but his claim to
fame was opposing the pelagian heresy which denied inherited
sin warpedness and upheld free will to such an extreme that
theoretically one could live sinless and not need a savior.
(yeah, well you still got to accept Jesus as your King or you are
engaging in sin right there.) The idea got ground that the Kingdom
of HEaven was the Church, and nothing more. that the devil
is bound now, though some argue the first millennium of the
church he was bound and is now loosed. But push this far enough
and you don't even have a literal Second Coming of Jesus Christ!

Sure the Church is an outpost of the Kingdom of Heaven, and we
are not to conquer the world for Christ and hand Him the Kingdom
we built, but recruit for the Kingdom of Heaven.

But what is the New JErusalem like? Here is what Revelation says,
after the new heavens and new earth,

"Then I, John, saw the holy city, New Jerusalem, coming down out of heaven from God,..." Rev. 21:2 THERE'S YOUR EVIDENCE. The NEw Jerusalem COMES DOWN FROM HEAVEN TO THE RESTORED EARTH. Rev. 21: 15, 16 "And he who talked with me a a gold reed to measure the city, its gates, and its wall. The city is laid out as a square: its length is as great as its breadth. And he measured the city with the reed: twelve thousand furlongs. Its length, breadth, and height are equal." "FURLONG fur'-long (stadion, "stadium"; Luke 24:13 John 6:19; John 11:18 Revelation 14:20; Revelation 21:16): A Greek measure of length, being 600 Greek ft., or 100 orguiai equal to 606 3/4 English ft., and thus somewhat less than a furlong, which is 660 ft." https://biblehub.com/topical/f/furlong.htm 606.75 feet x 12,000 = 728,000 divided by 5280 feet (1 mile) = 1378.98 (several sevens rounded off) 1378,98 miles high and wide. Like I said either you got an ongoing miracle here forever or the laws of physics get changed in the new heavens and new earth to allow this multistorey high rise city which by the way would cover about the same geography that was originally promised to Abraham's descendants not just Canaan alone. If each storey is 200 feet high then 728000 feet divided by 200 = 3640 layers. Each layer is 728,000 x 728,000 being a square = 529,983,000,000 sq. feet divided by 5820 feet (1 mile) = 100,375,757.58 after rounding off some digits square miles of space per layer. x 3640 layers - 365,367,757,575.76 (after rounding off some digits) total square miles of living space, room for trees, etc. That's over 365 billion square miles when you add all the layers up.