'Castle' in the Bible

And it came to pass, when Zimri saw that the city was taken, that he went into the castle of the king's house, and burnt the king's house over him with fire, and died,

And Pekah the son of Remaliah, his captain, conspired against him, and smote him in Samaria, in the castle of the king's house, with Argob and Arieh; and with him were fifty men of the Gileadites: and he slew him, and reigned in his stead.

and a letter unto Asaph the keeper of the king's forest, that he may give me timber to make beams for the gates of the castle which appertaineth to the house, and for the wall of the city, and for the house that I shall enter into. And the king granted me, according to the good hand of my God upon me.

that I gave my brother Hanani, and Hananiah the governor of the castle, charge over Jerusalem; for he was a faithful man, and feared God above many.

A brother offended is harder to be won than a strong city; And'such contentions are like the bars of a castle.