Isaiah 2:15

Every high tower - Towers, or fortresses, were erected for defense and protection. They were made on the walls of cities, for places of observation (compare the note at Isaiah 21:5), or in places of strength, to be a refuge for an army, and to be a point from which they might sally out to attack their enemies. They were “high” to afford a defense against being scaled by an enemy, and also that from the top they might look abroad for observation; and also to annoy an enemy from the top, when the foe approached the walls of a city.

Every fenced wall - הומה בצוּרה betsûrâh hômâh. The word “fenced,” בצוּרה betsûrâh, is from בצר bâtsar, to make inaccessible, and hence, to fortify. It denotes a wall that is inaccessible, or strongly fortified. Cities were commonly surrounded by high and strong walls to defend them from enemies. The sense is, God would overturn all their strong places of refuge and defense.