Built by Corik as a forward defensive position south of what is now called Corik's Wall, in the area known as the Lost Grounds. In naming his forward defense for the Elf-Queen of the Mountains, he hoped she would come at last to his city's defense but she proved false and left the Eloth and his city to the flames.
It was repaired and defended by the Emerald Knights after their founding in 183 and fell to the Dark Hand in 192 AV. This area became known as the Lost Grounds. An account of the early Knights and the Arm can be found in the The Emerald Chronicles by Geoff Graev.