Paper from the Towers, 10:25 a.m. Three and a half minutes after he shot this photograph, Bill Biggart was killed in the North Tower’s collapse. His cameras and film were recovered with his remains on September 15.   (Photo: Bill Biggart/SIPA Press)

As you looked down at the Towers from a distance on that perfect morning, the horror of it was abstract: smoke, a dull-red hole. There was also a glittering around the Towers, a further surreal touch. It took a while to sink in that this was paper—reams and reams of documents and legal briefs and loan agreements and minutes of meetings. The prevailing wind that day was blowing out over Brooklyn, and a highly incomplete record of the life of those two buildings ended up in that borough’s backyard