'Citadel' in the Bible

When Zimri observed that the city had been captured, he retreated into the king's palace, set fire to the citadel, and died when the palace burned down around him

Then King David addressed the entire assembly: "My son Solomon, the one whom God alone has chosen, is still young and inexperienced, and the task is great, since this structure will be a citadel to the LORD God and not for human beings.

Listen to me, and deliver me quickly. Become a rock of safety for me, a fortified citadel to deliver me;

For you have made the city a heap of rubble, the fortified city into a ruin; the foreigners' citadel is no longer a city it will never be rebuilt!

"For the palace will be abandoned, the noisy city deserted; the citadel and watchtower will become barren wastes forever, the delight of wild donkeys, and a pasture for flocks,

As I observed the vision, I looked around the citadel of Susa in Elam Province. While I watched, I found myself beside the Ulai Canal.