citadel

1. N-COUNT In the past, a citadel was a strong building in or near a city, where people could shelter for safety. (古时建在城市里或城市附近，保护民众安全的)堡垒

The citadel at Besançon towered above the river. 贝桑松城堡高过河面。

2. N-COUNT If you describe a system or organization as a citadel of a particular way of life, usually one you disapprove of, you mean that it is powerful and effective in defending that way of life. 堡垒; 指强有效保护型的生活方式[正式] [usu N 'of' n]

The business is no longer regarded as a citadel of commerce. 这个生意已经不再被看作是商业堡垒了。