John the Apostle
Revelation 21:16WEB·traditional attribution

The city is square, and its length is as great as its breadth. He measured the city with the reed, Twelve thousand twelve stadia. Its length, breadth, and height are equal.

Matthew Henry Presbyterian

We have already considered the introduction to the vision of the new Jerusalem in a more general idea of the heavenly state; we now come to the vision itself, where observe, I. The person that opened the vision to the apostle - one of the seven angels, that had the seven vials full of the seven last plagues, Rev 21:9.

Commenting on Revelation 21:9-27

Jamieson-Fausset-Brown Reformed

twelve thousand furlongs--literally, "to twelve thousand stadii": one thousand furlongs being the space between the several twelve gates. BENGEL makes the length of each side of the city to be twelve thousand stadii. The stupendous height, length, and breadth being exactly alike, imply its faultless symmetry, transcending in glory all our most glowing conceptions.

John Gill Reformed Baptist

And the city lieth four square,.... To the four corners of the world, from whence its inhabitants come, and denotes the regularity, uniformity, perfection, and immovableness of it. And the length is as large as the breadth; this church state will be all of a piece, perfect, entire, and wanting nothing.