Vagnoptus Manor in Sweden, base of the Klaashaa, backbone of The Dark, the primary antagonist faction. Damon Newcomb works for them. Vagnoptus, created by the infamous Count Magnus, exists as a permanent shallowing between dimensions with a direct portal to the Court of Azathoth. I plan to draw on House of Leaves for inspiration for the manor's layout. The manor will likely not appear directly but will act as a focal point for the story's masterminds. I may drop the heroes a hint as to the place's existence, though.
The Alta Vendita group who founded the Klaashaa is the Haute Vienne Coven, center of Dark activity in Western Europe.
The Klaashaa's P’Dwahr M’Ankanon tome will get added to the group of "new" tomes that I plan to focus on.