'Fortress' in the Bible

And David lived in the fortress. Therefore they called it the city of David.

And from the Gadites, valiant mighty warriors, {soldiers fit for war}, expert with shield and spear, defected to David at the fortress toward the wilderness. And {they had faces like lions} [and were] swift as gazelles upon the mountains.

And some of the sons of Benjamin and [from] Judah came to the fortress, to David.