Never forget

A stunning set of photographs taken by New York Police helicopters on September 11, 2001 has been released pursuant to an ABC Freedom of Information Act request last year.

A trove of aerial photographs of the collapsing World Trade Center was widely released this week, offering a rare and chilling view from the heavens of the burning twin towers and the apocalyptic shroud of smoke and dust that settled over the city.

The images were taken from a police helicopter -- the only photographers allowed in the airspace near the skyscrapers on Sept. 11, 2001. They were obtained by ABC after it filed a Freedom of Information Act request last year with the National Institute of Standards and Technology, the federal agency that investigated the collapse.

The chief curator of the planned Sept. 11 museum pronounced the pictures "a phenomenal body of work."

The photos are "absolutely core to understanding the visual phenomena of what was happening," said Jan Ramirez of the National September 11 Memorial & Museum. They are "some of the most exceptional images in the world, I think, of this event."

You can view the photographs here and here.