Mechanus, also known as The Clockwork Nirvana of Mechanus (or simply Nirvana) is a purely lawful aligned plane of existence. It is one of a number of alignment-based Outer Planes that form part of the standard cosmology.
It is the plane of ultimate law and order (neutral or chaotic creatures take -2 penalty on Charisma, Intelligence and Wisdom-based checks), where the souls of people of lawful neutral alignment go after death. Mechanus operates on a strict schedule where every action is planned, measured and controlled perfectly. It is home to the construct-like geometric modrons, the law-enforcing inevitables and the regimented giant ants called formians.