DIO Central was, obviously, the Department of Internal Operations's main base. The department has since closed, and the status of DIO Central is unknown.
Central itself is difficult to get to, as it is hidden in a maze of gravity distortions and urple, wilver, bleen, and blello walls that cannot be looked at without the observer going blind; part of the DIO's training involved learning to navigate this maze with their eyes closed. Once one is past the initial defences, Central consists of a larger-than-average response centre with two consoles that show feeds from security cameras all over Headquarters. The main room also has a weapon rack that serves as an armoury of sorts; in Nita Kerys's first recorded mission, Peter Piper claims that they have "almost everything" at their disposal, but that they tend to prefer ranged weapons due to the average agent's skill with a sword.
There are four doors leading out of the main room, not counting the maze exit; two of these lead to bedrooms, another to a bathroom, and the last to a cafeteria said to be better than HQ's main cafeteria. Control, where Agent Justin Agent stayed, is somewhere in the maze; Justin sent reports to Agents Piper and Kerys from there, along with monitoring the defences and trying to keep a lid on rumours of the DIO's existence.
It is possible to reach DIO Central in the PPC Computer Game, but the maze is a bit tricky to get through.