Ezekiel 41:6-7

6The side rooms were arranged one above another in three stories of thirty rooms each. There were ledges on the wall of the temple all around to serve as supports for the side rooms, so that the supports would not be in the temple wall itself.

7The side rooms surrounding the temple widened at each successive story, for the structure surrounding the temple went up by stages. This was the reason for the temple’s broadness as it rose. And so, one would go up from the lowest story to the highest by means of the middle one.