The Drawbridge                                         -      N      - 
(-------------------------------------------------)     - <---(M)---> -
                                                        -      S      -

The drawbridge itself is a work of art.  Massive wooden planks are
sandwiched on top of each other with magic and pressure forming a structure
sturdier then steel.  The boards are bound together with steel laden with
iron bolts.  The chains that raise the monstrosity are big enough for a
dwarf to step through.  The two sets of chains on either side run up into
the portcullis and are cranked up when there is a threat to the castle.