Before An Elevator Shaft                               -      N      - 
(-------------------------------------------------)     - <---(M)---> E
                                                        -      S      -

This small corridor leads south to a set of double sliding doors.  You
find that they are slightly difficult to operate, but ignoring the sign on
one of the doors you open them to reveal a small wooden platform beyond. 
There are a series of cables and pulleys attached to the platform, allowing
it to be lifted up to the level above.  To the north you can see an
identical setup at the other end of the corridor.