Found in Blackrock Depths.
Golem Lord Argelmach stands in a private room of the Manufactory, guarded by two elite golems. If threatened, Argelmach will draw all living Manufactory technicians and golems to eliminate adventurers. Before taking him down, adventurers would probably find it advantageous to kill all mobs in the Manufactory first to lessen the difficulty of the fight.
Argelmach holds Marshal Windsor's Lost Information, needed in the Alliance Onyxia chain quest. His head is also wanted by the Horde's Lotwil Veriatus.
Quest Objectives
Rise of the Machines (Horde)
Find and slay Golem Lord Argelmach. Return his head to Lotwil. You will also need to collect 10 Intact Elemental Cores from the Ragereaver Golems and Warbringer Constructs protecting Argelmach. You know this because you are psychic.\
A Shred of Hope (Alliance)
Return Marshal Windsor's Lost Information.
Marshal Windsor believes that the information is being held by Golem Lord Argelmach and General Angerforge.