Albert Barnes Commentary Ezra 6:4

"with three courses of great stones, and a course of new timber: and let the expenses be given out of the king`s house." — Ezra 6:4 (ASV)

The word translated “row” occurs only in this passage. Some regard it as a “course,” and suppose that after every three courses of stone there followed a course of timber. Others understand three “storeys” of stone, with a fourth “storey” of woodwork on the summit (compare to 1 Kings 6:5–6). Others consider that Cyrus intended to limit the thickness of the walls, which were not to exceed a breadth of three rows of stone, with an inner wooden wainscoting.

Let the expenses be given out of the king’s house - that is, “out of the Persian revenue,” a portion of the decree which was probably not observed during the later years of Cyrus and during the reign of Cambyses, and hence the burden fell upon the Jews themselves (Ezra 2:68–69).