stronghold
[noun]
Synonyms: fortress, bastion, bulwark, castle, citadel, fort

[TahlilGaran] English Synonym Dictionary ▲

strong‧hold /ˈstrɒŋhəʊld $ ˈstrɒːŋhoʊld/ noun [countable]

1. an area where there is a lot of support for a particular way of life, political party etc:
The area is a Republican stronghold.

2. an area that is strongly defended by a military group:
The fighters moved south to their mountain stronghold.

3. an area where there are large numbers of a rare animal:
one of the last strongholds of the European wolf

[TahlilGaran] Dictionary of Contemporary English ▲