'Bars' in the Bible

He also built upper and lower Beth-horon as fortified cities, installing walls, gates, and bars,

He had told Judah, "Let's build up these cities, surrounding them with walls, towers, gates, and bars. The land still belongs to us, because we have kept on seeking the LORD our God. We have sought him out, and he has given us rest all around us." So the people built and prospered.