Stronghold
Stronghold was a term used to indicate a well protected structure. 

Vulcans's T'Karath Sanctuary was a stronghold during a Vulcan civil war. ()

Elim Garak once called Deep Space 9 "a stronghold of his people's most hated enemies". ()

In late 2371, the former members of the Shakaar resistance cell headed to a stronghold on Kola Mountain. ()

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Architecture