Ezekiel 42:3, 19-20

Over against the twenty cubits which belonged to the inner court, and over against the pavement which belonged to the outer court, was gallery against gallery in the third story.

He turned about to the west side, and measured five hundred reeds with the measuring reed. He measured it on the four sides: it had a wall round about, the length five hundred, and the breadth five hundred, to make a separation between that which was holy and that which was common.