In World of Warcraft, Icecrown Citadel in Northrend sits atop the largest glacier on Azeroth, Icecrown Glacier in Icecrown. In here Ner'zhul transformed into the Lich King was cast into the world of Azeroth. Recently, the Scourge has created this massive fortress, surrounding the Frozen Throne that lies hidden underneath. Icecrown Citadel is the upcoming feature that will be added to the game in patch 3.3, making it the pinnacle of the Wrath of the Lich King raid instances.
Players can get into the Icecrown Citadel by finding the entrance in the mountains of southern Icecrown and it's surrounded by gigantic ramparts and massive, blade-like spires, the towers are an imposing landmark of the Icecrown skyline, emitting a beacon of light from its pinnacle.
Citadel stretches far under Icecrown and Icecrown Glacier, and the rift. The Frozen Throne itself was located on an island in the rift of the glacier towering above most of the underground Citadel.
In World of Warcraft: Wrath of the Lich King, Icecrown Citadel, so it might be home to the final encounter in Wrath of the Lich King, featuring the Lich King as the final boss, and its unknown if it is going to be killable or not. Although players interact with Arthas numerous times during the expansion, including during an event at Angrathar the Wrathgate in the Dragonblight, the instance where the final battle against him will take place is not expected to open until sometime after the expansion's release. This was somewhat remedied with the release of Sunwell Plateau, making Kil'jaeden the final boss encounter of The Burning Crusade, their goal is to ensure that Arthas does not become just another farm boss too soon before newer, more challenging content is released, as well as new challenge for you to make World of Warcraft gold.