Hallway of Worlds

The Hallway of Worlds is a strange place created by an ancient race, but clearly not part of the Ethereal Void.

It is a shimmering white place with huge columns that seem to go far into the sky. From that place, other worlds can be accessed. It is entirely possible that the Hallway is another dimension, since it is entered through a Black Gate (which, according to the Xorinite Wisp, enables interdimensional travel).

The Avatar entered the Hallway at the end of Ultima VIII with the help of the Obelisk, and went through it to return to Britannia.

The Hallway is a dimensional crossroads from which a person could enter any world or dimension desired.

Trivia

 * The design documents of Ultima IX reveal that the Hallway (in the document as the Nexus of the Worlds) was build by an ancient and powerful race, as a way-station to allow travel to any point in the universe at will.