The Icecrown Citadel is main base of operations of the Scourge and home of the dreaded Lich King. It is a location in the Warcraft franchise.
When the demon lord, Kil'jaeden, created the Lich King, he placed the dreaded master of the undead on a glacier that was later named Icecrown. Eventually, when the Lich King corrupted the human prince Arthas Menethil, the two fused souls and became one dreadful being. The fusion caused a great explosion that nearly destroyed the glacier, leaving a spire of ice in its place. At the top was a throne that the Lich King sat upon, and ordered his minions to build the Icecrown Citadel around the spire.
From the outside, the Icecrown Citadel looks like a mighty fortress, but instead it is a protective barrier to keep the Frozen Throne from harm. Most of the citadel's interior is below the surface of the glacier, filled with halls and rooms. At the top of the citadel is the Frozen Throne, where the Lich King commands his armies across the globe. Eventually, the citadel was assaulted, resulting in the deaths of some of the Lich King's greatest minions and the defeat of the Lich King himself.
While most of the citadel lies below the glacier, the three main wings are above. These three wings are the Plague Wing, the Blood Wing, and the Frost Wing.
The Plague Wing is the section of the citadel where the Lich King's most skilled scientists help create the Plague of Undeath. Led by the notorious Proffessor Putrecide, these scientists create not only plague but also some of the most horrific monsters the Scourge has ever unleashed, including the Abomination Twins Rotface and Festergut.
The Blood Wing is the section of the citadel where the elven San'Layn work on their studies and practice their blood magic. Led by Blood-Queen Lana'thel, the San'Layn Darkfallen have revived the Blood Princes, Valanar, Taldaram, and Keleseth. These three Blood Princes now work as Lana'thel's Blood Council, and protect her throne in the upper levels of the Blood Wing.
The Frost Wing is the section of the citadel where the Lich King's personal Dragonflight, the Frostbrood, rest. Led by Sindragosa, the Frostbrood dragons serve the Lich King unwillingly. Not only do the Frostbrood reside here, but a group of Vrykul also defend the Frost Wing, and a team of liches work to slowly drain the life out of the Green Dragon, Valithria Dreamwalker, and raise her as a new type of Frostbrood.