Seattle Underground

At approximately 2:20 p.m. on June 6, 1889, an overturned glue pot in a carpentry shop accidentally started the most destructive fire in the history of Seattle.

Vault lights (a form of walk-on skylight with small panes of clear glass which later became amethyst-colored) were installed over the gap from the raised street and the building, creating the area now called the Seattle Underground.

In 1907, the city condemned the Underground for fear of bubonic plague, two years before the 1909 World Fair in Seattle (Alaska-Yukon-Pacific Exposition).

[citation needed] Only a small portion of the Seattle Underground has been restored and made safe and accessible to the public on guided tours.

[citation needed][4] A second tour company, Beneath the Streets, was created in 2013 and explores different sections of Seattle's Underground network.

The Seattle Underground. The facade seen here was at street level in the mid-1800s.
Start of the Great Seattle Fire, looking south on 1st Avenue near Madison Street
A view looking upwards at the vault lights (glass skywalks). The roof of a building at previous street level; now the top of the glass is walked upon and forms the current sidewalk.
The concrete floor of the former meat market was originally at the level of the wooden platform on the left but sank over time because of decomposing sawdust fill.