Guard Checkpoint                                       -      N      - 
(-------------------------------------------------)     - <---(M)---> E
                                                        -      S      -

This station is where the cityguards check incoming citizens for
contraband, and where wanted posters cover the walls.  If a citygaurd
discovers a wanted criminal, they will be arrested before they can cause
harm to the city.
A city guard is checking for thieves and outlaws at the gate.
A gate policeman is here in case of trouble.