Although Orderly Chaos is set on the Disc, many of the specific locations would be unfamiliar to even the most avid reader of the book series.
The scene of The Drakhen Adventure's culmination; an dark and imposing hulk of a fort not far from the borders of Lancre, like so many ancestral homes in Überwald. The Drakhenians gather here for the (ultimately failed) implementation of their sun-eclipsing spell and the celebratory "dinner", which involved the release of human captives into the halls of the castle to be hunted by the vampiric cult members.
The main setting of The Grünwaldstadt Adventure. Grünwaldstadt began as a modest duchy, but under the hand of its newest ruler Wilhelm von Grünwaldstadt expanded within a few years to a kingdom the size of, incorporating for example Blintz, Stefan Kedon's hometown of Langweiligstrom and Geier von Engelmacher's former home of Lagerdorf.
Pan's erstwhile and Geier's current home.
As befitting a traditional vampire home, Castle Höllental (literal translation: "Hell-valley") is "imposing and foreboding, but well kept and extravagant"1, with tall double doors, plenty of gothic decorations and pointy black iron twiddly bits. The only rooms so far described in any detail are Geier's bedroom (makes up for lack of coffin with big chest of weapons; tidy and decorated in a stereotypically princely style; usually unoccupied) and Pan's (a mess, surprising for a vampire)2.
"Höllental" refers to the estate proper; the town attached to it and thus under the jurisdiction of the holder of the title Lord of Höllental is called Höllenstadt (literal translation: "Hell-town"). In Nightworld, it is a major vampire hub of activity.
Not a real place, of course. Except in the places where it is.
1The Grünwaldstadt Adventure, Orderly Chaos Forum, May 28, 2011.
2Homecoming, short story, Dec. 2010.