Oecumenius

And the city, it says, lies foursquare, and its length, its breadth, and its height are equal. The foursquare shape, as it seems to those skilled in these matters, is and is called a cube; for there is also a plane square; but when it is both square and equilateral in all dimensions, they say the cube signifies stability; for the good things of the saints are permanent and unchangeable, with no transformation corrupting their blessedness. …

Commentary on Revelation ↗

Bede

Its length and breadth and height are equal. This is the solidity of invincible truth, by which the Church, supported by the length of faith, the breadth of charity, and the height of hope, is not allowed to be carried about by every wind of doctrine (Eph. 4). If it lacks any one of these, the perfect stability of the Church will not be.

Commentary on Revelation ↗

Bonaventure

For if they are led twelve by twelve, they will be a hundred and forty-four, that is, the number of the City of Jerusalem. And so, a soul hierarchized in this way is a city in which God lives and is seen. John says of this: "He took me up in spirit to a mountain great and high, and showed me the holy city Jerusalem." And in the same chapter, he says that it was measured "to twelve thousand stadia." And, later, that "the length and the height and the breadth of it are equal." And that the measure of the wall was "a hundred and …

Collations on the Hexaemeron, Collation 23 ↗

Victorinus of Pettau

The city which he says is squared, he says also is resplendent with gold and precious stones, and has a sacred street, and a river through the midst of it, and the tree of life on either side, bearing twelve manner of fruits throughout the twelve months; and that the light of the sun is not there, because the Lamb is the light of it; and that its gates were of single pearls; and that there were three gates on each of the four sides, and that they could not be shut. …

Commentary on the Apocalypse of the Blessed John ↗