ABC News has obtained aerial photographs of the collapse of the Twin Towers taken in the immediate aftermath of the attacks. They were taken by Det. Greg Semendinger of the NY Police Aviation Unit, the only photographer allowed in the airspace around that time, according to the NY Times.
They make for stunning visuals. All of my visual memory of that day seems to contain images of the towers seen from the bottom up, of debris falling all around the people fleeing the carnage of building parts falling, of ash falling.
These pictures offer an entirely new perspective, especially when grouped together as aerial pictures - the ash looks like it's spreading sideways and up, not falling.