The Clockwork Nirvana is a strange realm, primarily located on the Lucidial plane but commonly bridges a gap between the Ludicial, Umbrial and Elemental planes. Home of the modrons, the realm consists of dozens of massive gears, maintained and powered by the modrons.
A realm of law and order, Nirvana had equal amounts of light and dark, heat and cold, and equal measures of the four elements. There was a place for everything and everything was in its place. Even individuals living here existed to fit into the greater scheme of things and thus achieve a perfect society. There was no pain, but the only pleasure was in successfully filling a role like a gear in a machine. Passion, fantasy, and illusion did not exist here, except for what might be brought in by visitors, and any who tried to foment individualism or stir passions for a cause soon found they were not well received.
Nirvana was connected to the Prime Material Plane via the Lucidial and Umbrial planes, as well as the elemental plane and was a welcome stop for people traveling on those dangerous realms.
Nobody knows who exactly built Nirvana, but the nature of the realm insists that it was created. Primus, the leader of the modrons openly admits that it is not the first ruler of the realm, and does not know the origins of the realm. The architecture and building methods, constantly replicated by the modrons, is identical to that of the Planar Observatory.