This article is about one of the outer planes of the Planescape cosmology from Dungeons & Dragons. For other uses, see Arcadia (disambiguation).

It is the land of perfection. It is where laws are made for the common good. It is the plane where harmony is born.

Arcadia thrives with orchards of perfectly lined trees, ruler-straight streams, orderly fields, and cities laid out in geometrically pleasing shapes. The mountains are unblemished by erosion. Everything on Arcadia works toward the common good and a flawless form of existence. Here, nothing intrudes on harmony.

It is said that everything on Arcadia is as perfect as it can be, neither as strictly regimented as Mechanus nor as devoted to the perfection of the individual as Celestia. But this is not entirely accurate. In fact, the inhabitants of Arcadia are often so convinced of their own righteousness that they are hard-pressed to recognize their own flaws. This likely contributed millennia ago to the loss of the bottommost layer of Arcadia, Menausus, which spiritually transmigrated to Mechanus, becoming one with the gear-works realm of ultimate law.

There is nothing native to Arcadia's two layers that does not contribute toward perfection and peace. The fields and forests are swollen with grain and fruit, all growing without tending or fear of infestation. Even the “wild” flowers grow naturally to create the most harmonious blend.

The trees of Arcadia are wondrous specimens. These great plants grow in both neat forests and straight-rowed orchards. Their bark has a copper, gold, silver, or iron sheen. Their leaves range from deep green to fiery red, but the leaves never fall. Fruit is always in season. On rare, wondrous occasions a plucked fruit suddenly manifests magical properties, The fruit is nonmagical until picked.

Vision is normal on Arcadia. Night and day are determined by the Orb of Day and Night atop Arcadia's tallest peak. Half the orb radiates light, and the other half is dark. It rotates evenly and without fail, lighting part of the infinite plane while another part falls into natural darkness. There is no dusk or dawn, just day or night.