From Longman Dictionary of Contemporary Englishthe citadel of somethingthe citadel of somethingliteraryPLACE a place or situation in which an idea, principle, system etc that you think is important is kept safe SYN stronghold the last citadel of freedom → citadel
Examples from the Corpus
the citadel of something• The U.S. is often seen as the citadel of capitalism.• The superbly sited Hellenistic theatres at the citadel of Pergamon and Termessos were only slightly altered in Roman times.• New Zealand became the citadel of the new right.• Deep structural changes will be necessary in developing countries if literacy is to go beyond the citadels of the elites.• Instead they concentrated all their energies on subduing the rebels' capital, the citadel of St Martial's.• Having emptied the citadel of gold and silver he left Limoges and went off in search of new sources of pay for his mercenaries.• That these people would one day be enthroned in the citadel of power could not have seemed conceivable to him.• In the citadel of St Martial everyone's nerves were on edge.• Look at it, the golden evening, the snowy mountains, the citadel of the Alhambra. 