Word for “place of power”
Solution 1:
Cathedral
The stage was her cathedral, where she felt as if she could conquer the world.
Used literally, a cathedral is where the Bishop's throne (or cathedra) is located. Used figuratively, it can be an important location of authority or power, with connotations of religious contemplation or being closer to the divine.
To Susan, an art gallery was her cathedral, her sacristy, her confessional, and her life’s work. (Source)
Solution 2:
Bastion suggestive of power
Also stronghold
Or zenith
Bailiwick