Seattle underground city
The Seattle Underground: Underground Paths - an abandoned city under Seattle, Washington, USA.
The Underground tours!!! So cool and spooky. Not sure about this particular company, but in general totally worth doing. Underground opium dens, prostitution, speakeasies and shanghaiing (see : en.wikipedia.org/...).
Seattle Underground Tours take you below the streets of Seattle to the city before the great fire
Seattle Underground Tour by nulaalaa, via Flickr
Underground; Seattle Washington. This place was so cool and creepy. Would love to go here again sometime.