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

And I will make thee to this people as a strong wall of brass: and they shall fight against thee, and shall not prevail: for I am with thee to save thee, and to deliver thee, saith the Lord.

And take unto thee an iron pan, and set it for a wall of iron between thee and the city: and set thy face resolutely against it, and it shall be besieged, and thou shalt lay siege against it: it is a sign to the house of Israel.