Like the reclusive wizard who inhabits it, the castle of Merlin is ancient, secluded, and rarely visited.

The original fortification was built around 450 BA in what was then the kingdom of Aevinn as part of the Great Castellation, but was abandoned during the Years of the Council. The wizard Merlin occupied and refurbished the structure around 550 YA and has occupied it ever since. He calls the site Caer Gysgodol, the "shaded castle".

The castle stands in the southern reaches of the Dark Forest near the Westsong River, about six miles northeast of the sea, and is surrounded by thick stands of trees right up to its walls.