Ezekiel 41:6-7

6And the side-chambers were in three stories, one over another, and thirty in order; and they entered into the wall which belonged to the house for the side-chambers round about, that they might have hold therein, and not have hold in the wall of the house. 7And the side-chambers were broader as they encompassed the house higher and higher; for the encompassing of the house went higher and higher round about the house: therefore the breadth of the house continued upward; and so one went up from the lowest chamber to the highest by the middle chamber.