stronghold
noun [ C ] uk/ˈstrɒŋ.həʊld/ us/ˈstrɑːŋ.hoʊld/
要塞，堡垒;据点
a building or position that is strongly defended
a rebel stronghold 叛军据点
They captured the last stronghold of the presidential guard. 他们攻占了总统卫队的最后一个堡垒。
（特定信仰或活动的）势力强大的地方，大本营，根据地
a place or area where a particular belief or activity is common
Rural areas have been traditionally thought of as a stronghold of old-fashioned attitudes. 乡村地区传统上一向被视为守旧思想的大本营。