'Citadel' in the Bible

The words of Nehemiah son of Hacaliah. It happened in the month of Kislev, in the twentieth year, that I myself was in the citadel in Susa,

Also, a letter to Asaph, keeper of the king's land reserve, that he should give me timber for laying the beams for the gates of the citadel of the house and for the walls of the city, and for the house which I will enter." And the king gave [permission] to me, according to the good hand of God on me.

I gave command over Jerusalem to my brother Hanani and Hananiah the commander of the citadel. For he was a faithful man and feared God more than many.