Secrets of the Ark of the Covenant

It wandered through the desert with the Israelite tribes, miraculously crossed the Jordan River with them, and in the Land of Israel struck terror into the hearts of Philistines and Israelites alike. What was it about the Ark that made it the holiest, most venerated object for the Israelite tribes? And why, when King David tried to mold Jerusalem into the spiritual center of the Jewish people, did the Ark of the Covenant play such a central role?