citadel

Etymology

From French citadelle, from Italian cittadella, diminutive of città (“city”), from Latin cīvitās.

noun

1. A strong fortress that sits high above a city.
2. (sometimes figurative) A stronghold or fortified place.
   Intrenched within the citadel of our apartment, and cheered by the comfortings of a coal fire, we passed the day in letter-writing, conversation, or gazing from the sheltered security of our windows upon the agitated sea[…] 1836, Alexander Slidell Mackenzie, The American in England, page 269
3. An armoured portion of a warship, housing important equipment.
   Twenty-two of these — eleven per broadside — were on the main deck within a central citadel, essentially an armor-protected box in the middle of the ship. Also within the citadel were four 110-pdr. breech-loaders. 2000, Lincoln P. Paine, Warships of the World to 1900
4. A Salvation Army meeting place.