Birth of a City
Seattle is a young city, even by the standards of the west coast. Until the mid-1800s there was nothing there but a stretch of tribal land and one sad little fur trading post. It wasn't until settlers started logging the climax forest around the trading post that any kind of real city began to be built and that wasn't until the 1860s.
From the first, the city had a reputation for being wildly permissive. They used to say that the only whores north of San Francisco were working out of Seattle, and while that might be a slight exaggeration, it wasn't much of one. There were laws and lawmen, nominally, but generally frontier justice prevailed. With, perhaps, a little subtle influence from the small and discreet Court of vampires who were nursing the city through its earliest years.
When the railroad reached Seattle in the 1870s, it brought civilization with it. All of a sudden there were women and luxuries to buy with the money, there were respectable jobs to be had and unions beginning to form. No longer a logging and fur-trading town, Seattle became a real city and gained a certain respectability to go with its ambition.
In 1889 a burning glue pot started the Great Seattle Fire, which burned 29 city blocks, nearly the entire business district. In the wake of the near-total destruction of the commercial areas of the young city, the city council made a decision that had no precedent in the modern age. They built a new city on the ashes of the last.
The Seattle Underground
The decision was made, with tremendous if subtle pressure from Shiloh and her people, to regrade the streets one to two stories higher than the original street grade. Pioneer Square had originally been built mostly on filled-in tidelands and, as a consequence, it often flooded. The new design filled in sections of the tidelands and raised the streets to 12 feet higher than before, in some places nearly 30 feet.
For the regrade, the streets were lined with concrete walls that formed narrow alleyways between the walls and the buildings on both sides of the street, with a wide "alley" where the street was. The naturally steep hillsides were used, and brick arches provide the ceiling for the underground corridors and support the hollow street sidewalks.
This created a section of several square miles where one city literally rests directly atop another. Skylights set into the sidewalks let purple-tinted light down into the streets below, and though the city tried to close off and condemn the underground, the city's preternatural population claimed the undercity almost from the first.
Yes, there are sections of the underground that are impassable from the debris and dirt. There are sections that are too dangerous for anyone but the druggies and the homeless to try to spend any time there.
But there are also sections, well hidden from the eyes of the general public, that are restored to a glory that the original city never boasted. Fantastic mansions buried beneath the sidewalks, accessible only through well-disguised entrances or through a sewer grate in a particular alley. There are clubs down there that the glitterati would pay a fortune to be able to find, businesses that cater to vampires and shifters and other, more exotic things. There's even a mall, of sorts, a strip of restored storefronts that some smartass dubbed 'Diagon Alley' where a monster could find any sort of treat they could never find topside.
It's a city within a city, alive and bustling, the real vampire district concealed by the sidewalks stretching overhead but also by the tourist-driven Vampire Disneyland of the public 'vampire district' in the city above, the section of town anchored by Many Moons that runs like an all-night fun fair for the benefit of the humans and to draw the world's attention away from what's really going on below.