Wall made by a plumbline — i.e., a perpendicular wall, the stability of the kingdom being represented by the closely-fitting well-jointed stones of a lofty wall. Right in the heart of this strong-built city, the Lord Himself marks the extent of the desolation, the plumb-line being used in dismantling buildings, as well as erecting them (2 Kings 21:13; Isaiah 34:11).
Related Commentaries of Amos 7:7
Amos 7:7
7 Thus he shewed me: and, behold, the Lord stood upon a wall made by a plumbline, with a plumbline in his hand.