A city in the Hollow World - this is the deepest point anyone from the Commonwealth has ever been. This is a bit of a disjointed place - non-violent prisoners are allowed to go here and be settlers, though it is worth mentioning there is a prison complex and they are still prisoners. There is an area of non-criminal settlers, and then the prisoners + their keepers, and the two are a bit divided and disjointed in this way.
This is where we heard Kovar Anranios was being kept prisoner, as well as a possible place Emer Kaine might be.
Built on the edge of a giant seemingly bottomless pit called The Howl that is “vantablack” in color. There are creatures that live in The Howl that can be caught and studied, and there are researchers that do absolutely do that.