'Fortification' in the Bible

He built the city around it, from the Millo (fortification) to the surrounding area; and Joab repaired the rest of the [old Jebusite] city.

Next to them Uzziel the son of Harhaiah, one of the goldsmiths, made repairs. Next to him Hananiah, one of the perfumers, made repairs, and they restored Jerusalem as far as the Broad Wall.