The winter air was cruel as I was walking last week toward the new Seattle Art Museum, and the sight of the museum's expansion—it looks like an office tower pushed up against another, taller Washington Mutual office tower—wasn't warming me up. So I put my head down until I got inside. "We're in a funny mood here," said Chiyo Ishikawa, the plenty hospitable chief curator of the museum, and I stared at the steel bars that blockaded the old special-exhibition gallery, which looked as if it had suddenly found itself in a bad neighborhood.

I find construction sites irresistible. This one is particularly so, considering the unusual, slightly grotesque nature of the project—turning the now-comatose 1991 Robert Venturi building into the butt end of a SAM that's mostly something else. Standing in the ruins of yesterday's lobby, I couldn't help but imagine that the remaining wires were sutures and the steel supports were arteries about to undergo the final stages of a surgical grafting by a mad doctor, before being awakened to the sight of a horrible self-mutilation.

The thing is, nobody liked the Venturi museum, or almost nobody. He designed a façade and a grand staircase that were pop-influenced, connective, and conversational, but his galleries were dark and insular. Circulating through his building meant riding blind in elevators, or climbing tucked-away stairs with no views. Our crew—Ishikawa, museum spokeswoman Cara Egan, construction project manger Joy Jacobson, and me—exchanged a few derogatory remarks about the Venturi galleries, and then prepared to cross over to the other side. We went into an expectant little pause chamber, and then the doors opened into the new construction zone with a blast of plaster scent.

"Here we are, in Europe!" Ishikawa declared, gazing at three massive, long rooms parallel to First Avenue. Visions of gilded frames and royalty and castles danced in my head, until Jacobson said, "Africa." In fact, we were in Africa. Or the place where the African collection will dwell. My associations roamed again. My mind scrambled to finish what was unfinished. The light was distracting because it was not under construction. It poured in from the First Avenue side, even through drawn vertical blinds.

The biggest galleries are at the front of the building, where the light comes in, and the ones the farthest back are much smaller; I began to imagine that the rooms had grown like photosynthetic plants, depending on their proximity to the light source.

We faced the light directly, and the conversation turned to the fact that most artworks can't do the same thing without damage. Poor Jacobson had to spend 15 minutes listing the baffling array of vertical blinds, movable walls, white nylon drapes, blackout shades, and light-diffusing shades that will manage this problem. Ichikawa, uncomplainingly, explained how, a decade ago, curators dreamt of a standalone building with top-lit galleries, but those aren't possible in a museum with an office building on top of it. I dreamed of other museums, too, and tried not to step on stray nails.