'City of David' in the Bible

Nevertheless David took the strong hold of Zion: the same is the city of David.

So David dwelt in the fort, and called it the city of David. And David built round about from Millo and inward.

So David would not remove the ark of the LORD unto him into the city of David: but David carried it aside into the house of Obededom the Gittite.

And it was told king David, saying, The LORD hath blessed the house of Obededom, and all that pertaineth unto him, because of the ark of God. So David went and brought up the ark of God from the house of Obededom into the city of David with gladness.

And as the ark of the LORD came into the city of David, Michal Saul's daughter looked through a window, and saw king David leaping and dancing before the LORD; and she despised him in her heart.