Desolation:

Caer Darrow

In the middle of Darrowmere Lake is a solitary island: the Isle of Darrow. The keep of Caer Darrow, perhaps the oldest Human monument in the world, stands upon this isle. In recent times, the ruling Barovs allotted Kel'Thuzad a place where he could conduct research which would help the Scarlet Crusade fight off the Horde. Unbeknownst to them, Kel'Thuzad's true allegiance is to the Burning Legion. Instead of marching off to fight the Horde, his experiments massacred the keep's inhabitants, turning them into Undead servants as well.