Icecrown Citadel

The Icecrown Citadel is the main base of operations/primary fortress of the Lich King from the Warcraft franchise.

Seated in the frozen wastelands of Icecrown, the citadel is flooded with the Lich King's powerful minions, forming a great army of undead soldiers. Over 250,000 of these minions populate the citadel, the fortress is extremely protected and heavily guarded.

Trivia

 * The citadel resembles Barad-dûr from the Lord of the Rings novels.