One of the Outer Planes in AD&D's Planescape setting. Mechanus was known as Nirvana in earlier versions of the game cosmology, but it was rightly decided that that was a) an unfair hijacking of a contemporary religious usage b) not what Nirvana really means. Mechanus is the plane of Lawful Neutral, and is themed on Technology. Modrons live there, and the whole plane is mounted on a series of many-mile-wide cogwheels. The Guvners are powerful here, and many legalistic deities like Hoar/Assuran, the Celestial Emperor and Primus live on Mechanus.