Built about 1957.
Definitely the least level lot I've encountered for an ALCOA house!
Superficially it appears to be fairly original but with a clear addition to the Southeast corner.
See also:
- http://www.zillow.com/homedetails/9121-NE-16th-St-Clyde-Hill-WA-98004/49128685_zpid/#{scid=hdp-site-map-bubble-address
- http://www.neighborcity.com/property/9121-Ne-16th-St-Bellevue-WA-98004-Any-5629012/