Hallway of Worlds

The Hallway of Worlds is a strange place. It is clearly not the Ethereal Void, but it isn't clear at all, what it is. 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.