Ezekiel 40:17-19

17Then he brought me into the outer court. And behold, there were chambers and a pavement, all around the court. Thirty chambers faced the pavement.

18And the pavement ran along the side of the gates, corresponding to the length of the gates. This was the lower pavement.

19Then he measured the distance from the inner front of the lower gate to the outer front of the inner court, a hundred cubits on the east side and on the north side.