'Citadel' in the Bible

When Zimri saw that the city was captured, he entered the citadel of the royal palace and burned it down over himself. He died

Then his officer, Pekah son of Remaliah, conspired against him and struck him down in Samaria at the citadel of the king’s palace —as well as Argob and Arieh. There were 50 Gileadite men with Pekah. He killed Pekahiah and became king in his place.

This is what the Lord says:I will certainly restore the fortunes of Jacob’s tentsand show compassion on his dwellings.Every city will be rebuilt on its mound;every citadel will stand on its proper site.