Bible Verses About Walls: Were probably often strengthened with plates of iron or brass

Toward this people I will make you a fortified wall of bronze they will fight against you but not prevail against you; for I am with you to save you and rescue you," says ADONAI.

Then take an iron griddle and put it in place as a wall of iron between yourself and the city, and fix your gaze on it - the city is under siege, and you are the one besieging it. This will be a sign for the house of Isra'el.