Cauldron?
Fortress implies it's heavily fortified and hard to get into/break down.
But for some reason I'm quite enjoying the idea of the alliteration of it being a cauldron. I also find the idea of a cauldron far more menacing. Not that the cottage needs to be mancing if people wanted it to be a fortress, but is cauldron now more intimidating?
With the corners along the Riverside now filled in and the cottage apparently louder than ever as a result a cauldron has a nice feel to it.
May be making something out of nothing but this is a conversation forum.
Agree that the new Riverside stand filling in the corners has helped to improve the atmosphere.