Before the Drawbridge                                  -      -      - 
(-------------------------------------------------)     W <---(M)---> E
                                                        -      -      -

The interior of this vast cavern is surrounded by some sort of natural
rock formation.  Curving gently to the north and south is a solid wall of
smooth black stone that reaches all the way up to the cavern's ceiling. 
There is an underground river running alongside the wall, and the only way
across is a large wooden bridge to the west.  You know that this must be the
Towne of Decara, one of the Alyrian Underground's largest population
centers.