Keep on the Shadowfell
A thousand years ago, cultists of the demon god Orcus raised a portal that led to the Shadowfell. On the other side lay a powerful unholy area that allowed Orcus' minions to bring forth all manner of evil undead into surrounding vale.
The empire of Nerath sent forth their legions to dispatch the threat, and after a bloody confrontation the undead were slain and the portal finally sealed. The imperial forces established a keep on the area to prevent the portal from ever being opened again.
Today, the Keep on the Shadowfell is but a ruin, though the lower levels are said to remain intact. The spirit of Sir Keegan is rumored to reside within, and goblins are reported to live among the rubble.