I went on the Underground Tour in Pioneer Square. The tour spanned the basements of two square blocks. There really wasn’t much to see, mostly concrete floor (the floor was sealed to stop a plague spread by rats) and wooden debris. The real value was in the tour guide, who recounted stories of Seattle’s history in entertaining detail.
Seattle was built on wetlands and had all kinds of issues with plumbing, landslides, fires. To mitigate these issues, the city proposed to elevate the streets over the course of many years. Businesses could not wait years to rebuild, so the compromise was for the businesses to have entrances on their second floors too. Then when the elevated roads were built, the second floor would be the new ground level, and the old first floor storefronts would be underground.
There was a period of time when the elevated roads were finished, but there were no sidewalks to connect the roads to the stores. People would have to climb a ladder up to the road, cross the road, then climb down a ladder to get back to ground level. The situation was extremely unsafe and dubbed the “one-step program” to alcohol rehabilitation, because people were one step from drunkenly falling off the second-floor-level-road to the ground floor below.
On some sidewalks of Pioneer Square, there are translucent purple tiles. These tiles provide light to the underground tunnels below. The arched sidewalks that connect the road to the storefronts have held up well and are still used today.
One interesting tidbit from old Seattle plumbing: flushing the toilet during high tide could cause the contents to flow in reverse, so that there was a fountain of crap spewing forth from the toilet.
Early settlers of Seattle were incentivized to move by offers of free land. Most of Seattle’s city budget came from a tax on “seamstresses,” which is what the women had self-reported as their occupation in a census. During the Alaskan Gold Rush, that’s when Seattle’s growth exploded. Seattle was the starting point of the journey, where people would go to get supplies.