The Outlands

From Manuel of the Planes (3e):

It is the meeting place of opposed alignments.

It is the fulcrum of the Outer Planes.

It is the hub of the Great Wheel.

The Outlands is unique among the Outer Planes because it borders all other Outer Planes. As a result, it is the common ground for extraplanar creatures. Beings from infernal and celestial planes, as well as those of law and chaos, can be found here. In addition, deities of true neutrality or ideals such as scholarship or nature have their realms here.

The Outlands is an infinitely large wheel with a great spire rising from its center. Outlanders consider this towering cylindrical plinth as the heart of the Outer Planes and the axle around which the Great Wheel spins. This great plinth is clearly visible from anywhere in the plane, as it rises above the clouds themselves and ascends into unreachable heavens. The City of Doors, Sigil, floats at the top of the spire.

The Outlands itself is a broad region of varied terrain, with open prairies, towering mountains, and twisting, shallow rivers. There are settlements throughout the area, inhabited by petitioners and other natives of the plane. But they are small flecks against the greater wildness of the Outlands.

The Outlands is relatively open space once you get beyond the portal towns and the domains of the neutral deities. Rolling, grass-covered hills, deep canyons, thick forests, and sharp-toothed mountains dot the landscape.

The Outlands has a cycle of day and night similar to that of the Material Plane, although there is no obvious sun or stars. During the day, the sky simply brightens; 12 hours later, it darkens for night.

In the Outlands, heavy fogs and mists are common. Travelers occasionally get lost and wind up closer to unfriendly portal towns than they anticipated.