Ezekiel 41:6-7

6The side rooms were on three levels, one above another, thirty on each level. There were ledges all around the wall of the temple to serve as supports for the side rooms, so that the supports were not inserted into the wall of the temple. 7The side rooms all around the temple were wider at each successive level. The structure surrounding the temple was built in ascending stages, so that the rooms widened as one went upward. A stairway went up from the lowest floor to the top floor through the middle floor.