Ezekiel 40:17-21

Then he brought me into the outer courtyard, and behold, there were chambers and a stone pavement made for the courtyard all around; thirty chambers faced the pavement.

And the pavement (that is, the lower pavement) was by the side of the gates, corresponding to the length of the gates.

Then he measured the width from the front of the lower gate to the front of the exterior of the inner courtyard, a hundred cubits on the east and on the north.

And as for the gate of the outer courtyard which faced north, he measured its length and its width.

It had three guardrooms on each side; and its side pillars and its porches had the same measurement as the first gate. Its length was fifty cubits, and the width twenty-five cubits.