Jerusalem is builded as a city that is compact together. In David's time the upper and lower city were joined together, the streets regularly built, the houses contiguous, not straggling about, here and there one .
So the church of God, like that, is built in a good situation, on a rock and hill, where it is firm and visible; like a city full of inhabitants, governed by wholesome laws, under proper officers; a free city, which enjoys many privileges and immunities; a well fortified one, having salvation for walls and bulwarks about it; a royal city, the city of the great King, the city of our God, the name of which is "Jehovahshammah", the Lord is there: and this is "compact together" when its citizens are united in affection to one another; agree in their religious sentiments; join in social worships, and live in subjection to one Head and King, the Lord Jesus Christ.
The Jews often speak, and so some of their commentators on this passage, of a Jerusalem above and below, and of the one being made like unto the other: so the Targum,"Jerusalem is built in the firmament as a city, as Jerusalem on earth;''see Ga 4:26.
Hecataeus, an Heathen writer, describes Jerusalem as a strong fortified city, fifty furlongs in circumference; and inhabited by twelve myriads, or a hundred and twenty thousand men. Vid. Euseb. Praepar.
Evangel. l. 9. c.