Old House is Swayne's fortress and headquarters in the Shadowfel. Interestingly, it's in the exact same place that Castle is in the Fadelands, although whether that's just because it's a very defensible position in both planes or because of some more esoteric force is up for debate.
As well as Swayne and his various lieutenants, servants and retainers, Old House is home to Swayne's herd of "human cattle". These are Humans kept under Swayne's protection but without access to proper education or society. Every day he eats one of them to fulfill his vampiric need for blood.