The main Gables building (with 28 units) was built in 1911, and both the main building at 409 16th Avenue East and the “Annex” building (with 6 units) at 403 16th Avenue East appear in a 1912-dated Baist Real Estate Map of the city digitized by Ron Edge of Paul Dorpat’s excellent Seattle history web-site. The street was called 16th Avenue North at the time. http://pauldorpat.com/rke/html/baist/index.html
The architect’s visualization of the building from a September 9, 1911 article in Pacific Builder and Engineer is stimulating plans to restore the street appearance of the grounds.
The adjacent Seattle Firehouse No. 7 facing 15th Avenue East was built in 1920 and is now occupied by a video store. A 1921 photograph shows the firehouse and the back of the Gables Annex. http://www.flickr.com/photos/seattlemunicipalarchives/3385467616/