A thousand cubits. — Not so much “built” as “strengthened.” This comparatively large space — mentioned in round numbers — had probably suffered less damage, and therefore needed less repairing.
Related Commentaries of Nehemiah 3:13
Nehemiah 3:13
13 The valley gate repaired Hanun, and the inhabitants of Zanoah; they built it, and set up the doors thereof, the locks thereof, and the bars thereof, and a thousand cubits on the wall unto the dung gate.