Driving back from the coast we spotted this... Or rather, it loomed up on us!

Turns out this WWII US Navy Blimp Hangar in Tillamook, Oregon, is the largest clear-span wooden structure in the world, covering 7 acres!! (327m x 90m) built in 1942. #neverknowwhatyoumightfind

Thanks to MDTS for this link which shows some great construction photos! 

http://www.pdxhistory.com/html/tillamook_blimps.html