1) Siren's Sanctorum
Reasoning: The Sanctum Sanctorum generally refers in Latin texts to the holiest place of the Tabernacle of the Israelites. Since you are the Count, your city/seat of power is the most important/"holiest" place of the County.
2) Siren's Secret
3) Siren's Soul
Reasoning: The seat of power could be considered the "Soul" of the County its self.
4) Siren's Serenity
5) Hangman's Hollow
Reason:
6) Hangman's Holler (based on old name)
7) Siren's Song
8) Siren's Silence
9) Seamount Stronghold
Reason: Since it will be beside a mountain
10) Siren's Stream
Reason: Since it will be near a shallow river.