The Iron Fortress was a citadel in the Dragon Kingdom from which the Iron Queen and Iron King sought to dominate all of the Dragon Kingdom. It included an armory housing many captured weapons, including the Fan of Fen Xing. The evil duo were forced from this location by Sonic the Hedgehog, Miles "Tails" Prower, and their nemesis Monkey Khan after they infiltrated the fortress and used the fan to defeat the two. (StH: #60)
The pair later reclaimed their fortress sometime before the Iron Dominion's taking possession of New Megaopolis. After their departure from the Dragon Kingdom, it became a base for the Raiju Clan as they enforced the Dominion's will. It was then stormed by the allied forces of its three former invaders, Sally Acorn, and the Destructix under Fiona Fox, leading to a pitched battle that ended with the Raiju Clan forsaking its loyalty to the Dominion and claiming the fortress as its own. (StH: #200, SU: #15)