The large rectangular black palace is located north of the Teleport Gate plaza of the Town of Beginnings and is encircled by large castle walls and a moat. The palace was assembled with black glossy pillars and metal boards, had a tall and large front gate, iron floors and an abnormally high ceiling. The air within the palace is significantly cooler than outside.
There was a Hidden Dungeon under the palace, likely to be unlocked by fulfilling a certain condition on the higher floors. It was also used as a headquarters and prison by the Aincrad Liberation Force (The Army), usually for «Orange Players». Players violating the Harassment Prevention Code may be teleported to the Black Iron Palace's prison, if the victim chooses to select this option on the system prompt that appears when the system detects a breach of ethics. Players can also be sent to the prison with the use of Corridor Crystals, the destination of which is set for the prison.
In the Beta version of Sword Art Online, the palace housed the game's re-spawn point, called the Room of Resurrection. However, in the official version of the game, the Room of Resurrection was replaced by the Monument of Life, which kept track of the deaths of the SAO players. When Aincrad was later incorporated into New ALfheim Online, the Monument of Life was replaced with the Monument of Swordsmen, keeping track of the names of the participants of successful Labyrinth Boss raids. The monuments are placed in the hall right after entering through the main gate. Only this hall was open to the public at all times, while the deeper parts of the palace were under the control of the Aincrad Liberation Force by November, 2024.