You've heard of war bunkers and subways and fallout shelters, but this list of hidden places has more than I ever knew about, like how Seattle created an underground level in one fell swoop.

The Great Seattle Fire of 1889 put an end to the first Seattle, with civic leaders making two important decisions. The first was a building ordinance specifying that all new constructions must be of brick or masonry. The second was to elevate the new city above the tideflats, effectively turning the second story of buildings into the new ground floor. Shop-keeps quickly rebuilt, and sidewalks and streets were planted one story higher than before, creating underground passageways lined with the original storefronts.

There are 15 other places and stories as well at Nile Guide. Link -via Holy Kaw!

(Image source: Sights in Seattle)