The story of Seattle’s underground commerce is pretty interesting (http://en.wikipedia.org/wiki/Seattle_Underground). Mashable has a great photo essay on the re-grading of Seattle’s landscape which explains how the underground businesses were created:
“Following a fire which razed much of the downtown area, City Engineer R.H. Thomson took the opportunity to spearhead a wide-ranging effort to tame the terrain around the city and prepare it for a century of growth.
Canals were dug, rivers were diverted and mountains were moved.
In particular, the glacial hills and ridges which separated neighborhoods from the downtown waterfront were deemed a major impediment to travel and commerce, and a prime target for removal.
From the 1890s through the 1920s, more than 50 million cubic yards of earth were scraped away with pick axes, water cannons, steam shovels and conveyor belts. Much of the displaced earth was used for filling in tidal flats on the waterfront.”
Basically a dispute between private landowners and the city prevented anyone from taking responsibility for building sidewalks once they’d regraded the road about 15 feet higher than what it had been previously. Eventually they compromised, shared the expense and built the sidewalks. But a number of businesses at ‘street level’ suddenly became basement real estate. Having become a great deal more discrete they inevitably lent themselves to a literal and figurative underground economy of mini casinos, bars, opium dens and brothels. among other places- most of which are now unrecognisable – the tour took us past the remains of a booth for what was probably the first 24-hour bank teller. You can’t even find that in Melbourne and it’s been a hundred years.