'Royal house' in the Bible

Also Vashti the queen made a feast for the women in the royal house which belonged to King Ahasuerus.

And Esther was taken to King Ahasuerus into his royal house in the tenth month, which is the month Tebeth, in the seventh year of his reign.

And it happened on the third day, Esther put on royal clothing, and stood in the inner court of the king's house, across from the king's house. And the king sat on his royal throne in the royal house, across from the gate of the house.

But do not prophesy again any more at Bethel; for it is the king's temple, and it is the king's royal house.