He built the high gate of the house of the Lord - situated on the north - that portion of the temple hill which was high compared with the southern part - hence “the higher,” or upper gate (see on 2Ki 15:35). He built, that is, repaired or embellished.
and on the wall of Ophel - Hebrew, “the Ophel,” that is, the mound, or eminence on the southeastern slope of the temple mount, a ridge lying between the valleys Kedron and Tyropoeon, called “the lower city” [Josephus].
he built much - having the same desire as his father to secure the defense of Jerusalem in every direction.