And David lived in the stronghold and called it the city of David. And David built the city all around from the Millo inward.
If Salem, the place of which Melchizedec was king, was Jerusalem (as seems probable from Psa 76:2), it was famous in Abraham's time. Joshua, in his time, found it the chief city of the south part of Canaan, Jos 10:1-3. It fell to Benjamin's lot (Jos 18:28), but joined close to Judah's, Jos 15:8.
Commenting on 2 Samuel 5:6-10
So David dwelt in the fort,.... The strong hold of Zion, which he took: and called it the city of David; from his own name, to keep up the memory of his taking it, and of his habitation in it: and David built round about, from Millo and inward; built a wall about it, and enlarged the place, increased the buildings both within and without.
David dwelt in the fort, &c.--Having taken it by storm, he changed its name to "the city of David," to signify the importance of the conquest, and to perpetuate the memory of the event. David built round about from Millo and inward--probably a row of stone bastions placed on the northern side of Mount Zion, and built by David to secure himself on that side...