The keep some of ya'll are in now used to be a small fortress guarding Udny Pass, back when it was actually just a pass.  The city grew up around it and it's been renovated several times in the intervening centuries.  It's become the seat of power in Greenbank.

Or that's how I'm envisioning it.  It's either situated in the middle of the city, or on a particularly defensible edge of it.