The Egreth Castle served as the seat of royal power from the reign of Duncanthrax (who moved the capital from Largoneth in 660 GUE). Protected from hostile invaders from the sea by Fort Griffspotter, Egreth also happened to be the major sight in the Westlands of the vast tunneling project implemented by Duncanthrax to move the Empire underground. He also built the Glass Maze there to amuse his friends and to scare off his enemies.
In 758 GUE King Mumberthrax commissioned his 17-year old son Frank Lloyd Flathead to design a new wing for the Castle. The breathtaking wing made Frank Lloyd the hottest architect in Quendor. Two years later the wing collapsed killing over 4000 royal guests. This was credited to a miscalculation by the stonemason, who was summarily executed.
Its glory ended with the reign of Dimwit Flathead (who built a new castle in Aragain and moved the capital to Flatheadia in 771 GUE). When Egreth was deserted, it became home of evil creatures and wizards. Egreth was, and still is, reputed to be the most dangerous locale in the kingdom.
During his control of the area surrounding Egreth Castle, Jeearr was using infernal machines to breed mutated grues that were not afraid of light. Luckily for mankind, these grues were never released into the world at large. Egreth was best remembered in the magical community for the famed CoalWalkers of Egreth, a troupe who used magical aid to protect themselves while carrying out their stunts.
Egreth was also the home of the necromancer Radnor who sought the Amulet of Egreth of his former master, Thorman. Eventually he found it in the possession of a caravan near him. He kidnapped the woman he though Thorman's granddaughter but her companions moved to rescue her. Eventually Radnor was dematerialized by the true heir of the amulet, Lia. Thorman's spirit lifted the curse of the Castle and revealed that it now belonged to Dirinthrax a descendant of Duncanthrax.