All know that Elves cannot die, and that Men do. All know that Men go unto the Underworld upon their death, and that the Elves retire unto the Spiritual Elysium. Yet in the Great Scheme, where goes the one with one foot in the Underworld, and one foot in the Realm of Spirit?
You come upon a ruined building in the back section of a city park (or other out of the way area of the city). The ruins are fairly overgrown. All that is really standing is a doorway and its frame. If you pass through the opened door, you travel to a different world. If the door closes, there may not be a doorway back to get you back.