And he measured its WALL, seventy-two YARDS,
We assume that this is the thickness of a wall that reaches from the foundation to the top of the new Jerusalem (verse 12). While most commentaries dwell on the physical dimensions of the new Jerusalem, the importance of the theological symbols must not be overlooked. In the previous verse, we showed that the new Jerusalem is a view of the most holy place in the temple, That is, a covenant was established between God and a chosen people (verse 12 and Genesis 17:1-8); our Savior, Jesus Christ, came from this chosen people (Luke 2:1-7); and this Jesus Christ's teachings (theology) was spread around the world by the apostles (verse 14). All who are residents of this new Jerusalem are there because of a SPIRITUAL commitment they made to Jesus Christ.
Now to the wall, in particular, we know that the wall is for protection. The wall must be made up of a select group of spiritual entities that will protect the new Jerusalem. In Revelation 7:1-8, we find a select group of bondservants sealed for God. While nowhere is it explicitly stated that the wall is the residence of the 144,000 bondservants, but inasmuch as the gates through this wall have the names of the 12 tribes of the sons of Israel (verse 12), this may be the case.
according to human measurements, which are also angelic measurements.
As for the human and angelic measurements being the same, we probably are shown the 'after resurrection' (Revelation 20:5 and Revelation 21:8) life equivalency of angels and the redeemed (Luke 20:27-36-40).