Said to be the remains of the ancient Eastern Empire (c. >800 BE), the castle at Fenshire was once the summer palace of the Kings of Quendor, used by the descendants of Duncanthrax (possibly the Bellicose himself) and even Dimwit Flathead. Many saw this vile, dangerous region as being quite fitting for the Flatheads (although anyone saying that too loudly would often find themselves a little closer to the vile, dangerous creatures then they would like. Most often, they'd be suspended upside down over a pit of Fenshire alligators which have the words "See the Difference?" painted on their backs. The Flatheads were renowned for their inventiveness, if not for their sense of humor.)

Although Flathead had a gondola system with sister hangars built to connect both Flatheadia and the Summer Castle, by 883 GUE, it lay in ruins, unoccupied and uncared for, forgotten for many years and almost completely hidden beneath untamed marshland.

Today the ceilings of the main hall are collapsed, its frescos are faded, the glass of the arboretum is broken, foliage has run wild as the swamps have encroached over it almost entirely. One of the most famous frescos, which is hotly debated by scholars, is one depicting the death of Duncanthrax: his spirit is ascending to heaven on a tremendous ladder, surrounded by a host of angels.

In 883, the First Dungeon Master and Megaboz (in the disguise of a royal jester) visited this castle as part of their quest which ended in the collapse of Flatheadia.