The old tuna cannery down in the flats of Bayview Hunters Point has, technically, been sitting empty ever since it was condemned after the '89 quake.But one peek inside the immense building - now completely boarded up and guarded by a tall chain-linked fence - reveals it has hardly been abandoned. What appears on the outside as an industrial wasteland is, on the inside, perhaps the largest living canvas for graffiti artists in the entirety of San Francisco. And it won't be around for much longer. A representative for Caltrans, which has owned the property since the mid-1930s, confirmed that the building is scheduled for demolition some time in mid-September. For Caltrans, the demolition symbolizes a long-awaited victory. But for a small collection of unruly stakeholders -- homeless, metal scrappers, junkies, graffiti artists, urban explorers, rats, pigeons, and photographers -- it will mean the loss of something they have reclaimed as their own. We visited the warehouse recently to capture the some of the secrets this fortress hides behind its looming exterior before it is destroyed.