The Black Citadel
The Black Citadel is a fortress that lies in the southwestern Mavian Swamps and is the seat of power for Thanatos. It is a place where the powerful rule over the powerless and greed is felt throughout the vast fortress-city's black walls.
The Northern Citadel by Toby Lewin
I personally think that you should go in depth about the lore for the Black Citadel as it sounds very interesting and I can see much oppertunity for lore to be told!