the Dresden Files-Twin Cities
There is the mortal world, which includes the universe as known by mortals, and then there is the Nevernever. The Nevernever is also known as the spirit world, the immaterial world, and a host of other names derived from various cultures and mythos. It is completely mutable, and malleable, a strong will can shape the Nevernever to whatever form it wishes. Fairy makes up a large part of the Nevernever closest to the mortal world, with Summer and Winter each with its own vast kingdom. Other powerful entities or spirits likewise have their own domains within the Nevernever. Anything and everything ever imagined, or that will be imagined, has a place there, as well as things that may never be imagined by mortal minds. Any afterlife, other worldly realm, or alternate dimension likely exists there as well.
The Nevernever is connected to the mortal world in various ways. A place that is dark and spooky in the mortal world will open to a corresponding area of the Nevernever. This attribute allows a wizard or other practitioner to open a way to the Nevernever, travel a short way, and open a way back to the mortal world that could be on the other side of the earth from where he started (though not without dangers)
Any creature or spirit summoned by a mortal originates in the Nevernever, and magical constructs are formed using matter from the Nevernever (though once no longer powered by magic, these constructs revert to gelatinous goop, which shortly disappears altogether)