A few more... After the 1889 fire, Seattle spent a number of years raising their streets to higher levels. While that was underway, though, they left the original sidewalks in place. Eventually they roofed them over and created tunnels below the new sidewalks, but they installed skylights to allow people and businesses to continue operating down there. These are a few shots of the skylights, from below and above.
Jim
View from below (complete with a garden!)
one taken out of service, the prisms were used to disperse the light more down below...
Topside view of a skylight still in place in the current sidewalk