In the dank,dense areas of the world where the vigorous and the decaying are intertwined and indivisable, lives the wise bagabond. But getting him to impart his knowledge is quite a chore.
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.