Apparently this is a landmark -- the former dwelling of folks looking for cheap breakfasts at all hours, often to battle impending or incumbent hangovers.
According to a Seattle Times article, "A city board stunned developers, preservationists and Ballard residents Wednesday by voting 6-3 to designate the boarded-up Denny's Restaurant at Northwest Market Street and 15th Avenue Northwest a landmark — based largely on the visual punch the structure's Googie-esque roofline delivers to passing motorists."
Property owner Benaroya Companies acquired the site in 2006 for more than $12 million and intended to sell it to a condominium developer. Now they're screwed because the city board rejected its own staff's recommendation and proclaimed the old Denny's a landmark because of the building is "an easily identifiable visual feature of its neighborhood" and contributes to the identity of Ballard.
A local historian told the Times, "Ballardites proudly called it the Taj Mahal of Ballard."
I'm a Ballardite. I call it the shitty Denny's on the corner, but whatever.