Ezekiel 41:5-7

He measured the wall of the Temple. It was ten and a half feet thick. The side rooms around the Temple were seven feet wide. There were three floors of these side rooms, thirty rooms on each of the three floors. There were supporting beams around the Temple wall to hold up the side rooms, but they were freestanding, not attached to the wall itself. The side rooms around the Temple became wider from first floor to second floor to third floor. A staircase went from the bottom floor, through the middle, and then to the top floor.