There is a lot going on under the streets of Seattle!
Tested Travel opted to take the super-touristy Bill Speidel's Underground Seattle Tour. It was goofy fun!
Areas closest to the harbor was rebuilt after a massive fire leveled the young Seattle in 1889. In rebuilding, city planners raised the street levels (which also fixed some serious plumbing problems!). As they were lifting the streets, some of the former structures were still in use. When eventually abandoned for the new street-level entrances, the former buildings (now basements) were just left to the spiders and rats.
This creates an entertaining, historical, interesting tour of the old city. You will learn about the shops, and people who lived in the area, the bad plumbing, shady characters, and building mishaps.
A word of note to the younger Tested Travelers -- some of the tour narratives involve lurid tales and bad language. Something to be aware of.
Read more about the Seattle Underground Tour here.