stronghold | English Words
Air strikes pound Syria's last rebel strongholds, gas chokes civilians
stronghold
[Pronunciation: 'strȯŋ-ˌhōld Function: noun Date: 15th century]
If you say that a place or region is a stronghold of a particular attitude or belief, you mean that most people there share this attitude or belief.
The seat was a stronghold of the Labour party.
= bastion