Collapsed Corridor                                     -      #      - 
(-------------------------------------------------)     - <---(M)---> E
                                                        -      -      -

You are in a twisting corridor made of roughly worked plain gray stone. 
The stone is cracked and broken, making it loose and unstable.  The western
end of the corridor has collapsed completely, preventing you from going any
further in that direction.  Through a layer of broken stone debris, loose
dirt, and dust, you can barely make out a dull mosaic of blue tiles set in
the floor.  There is an iron door to the north.  The corridor continues to
the east.