The un-door is a brick frame of a door in the middle of a building's wall. It looks like they just decided to take the door out and fill it with cement or something. We're pretty sure the building belongs to a wizard and that it's a portal. We can't go through it because as everyone knows you can only enter a Wizard's home by invitation. There is evidence of thieves around the building as we discovered bricks falling out of the wall in various places where we're pretty sure someone is trying to bust in, however the bricks disappear everytime we visit it so we think the house magically repairs itself.