Ezekiel 41:5-7

5Next he measured the wall of the temple to be six cubits thick, and the width of each side room around the temple was four cubits.1 6The side rooms were arranged one above another in three levels of thirty rooms each. There were ledges all around the wall of the temple to serve as supports for the side rooms, so that the supports would not be fastened into the wall of the temple itself. 7The side rooms surrounding the temple widened at each successive level, because the structure surrounding the temple ascended by stages corresponding to the narrowing of the temple wall as it rose upward. And so a stairway went up from the lowest story to the highest, through the middle one.