Side Exit to Castle                                    -      #      - 
(-------------------------------------------------)     - <---(M)---> E
                                                        -      -      -

You are at the side exit of the Castle.  The King had this exit made to
prevent oncoming assaults on the gate.  It can fit no more than one person
through the doorway.  The door is made of stone and matches the wall
exactly.  From a good distance away this exit could not be detected.