If it was a castle, it was the strangest one he had ever seen.
He of course saw the main tower - taller than anything he had seen outside of Stoneholt, the spire looked fragile and was topped by a glassed-in chamber.
The outer wall was so gently sloped that it would have only stopped a horde of hobbling old men, an able-bodied soldier could stride up to its crest with little effort. Within one saw a huge, nearly perfect bowl-shaped area with the base of the tower in the centre, covered in hundreds of mirrors.
This structure is a massive solar collector designed by the Wizard-King Aardwal in centuries past. He used the concentrated light in his investigations into the magic of light, and in the fashioning of flash crystals.
The runoff from Mount "Evil Volcano" has turned an area of small lakes below into a vision of hell. The mixture of acids in the lakes is of such strength that virtually any organic material touching is quickly dissolved. It is a melange of sulfuric, nitric and hydrochloric acids.
However, the place does harbor life, and its very strange, and very dangerous....
Arakis's zombie problem went largely ignored, because it was believed that the Shai-Hulud (sand worms) would effectively dispose of the undead walkers. Unfortunately the problem grew until the roving herds of sunburnt ghouls threatened the flow of spice. While observing one of the great reanimated masses over take a Harvester from the safety of an ornithopter, an Imperial Zoologists noted that the sand caked flesh eating revenants walked entirely without rhythm.
Shortly after receiving this report the Bene Gesserits claimed to have a solution to Arakis's hellish resurrections. They asserted to the agents of the great houses that the worms could be drawn to the walkers using an ancient sonic weapon. According to the sisters, exposing the zombies to an antediluvian ballad composed by the great master M. Jackson would force them to step in time.