Mordion Gaol is the most unique area in all of Final Fantasy XI. It exists outside of any conquest area. It can only be entered or exited at the direction of a Game Master (GM), and that said, this is not a place you want to be as a player. Mordion Gaol is quite simply a place that a GM will place a character who has violated the user's agreement in such a way not to be summarily banned, but to such a degree that he needs to be addressed without distraction by the powers that be. The Gaol has 32 rooms, none of which can be communicated between. Magical transportation methods are disabled. Linkshell, party, and tell communication is disabled. The player has no choice but to listen and be attentive to the GM and hear the sentence for his misdeeds.
Gaol is a British term that is both pronounced as and means the same thing as the modern word "jail".