Archivists who bought a stash of CDs at a house clearance sale found 2,400 photos of Ground Zero in New York taken following the 9/11 attacks in 2001.
They appear to have been taken by an as yet unidentified construction worker who helped to clear up the wreckage of the World Trade Center towers and surrounding area.
The CDs were in poor condition but the data was ultimately retrievable.
The archivists have uploaded the photos to Flickr.
The digital albums include images of Ground Zero itself taken both at ground level and from above, construction staff at work and the damaged interiors of the blocks surrounding the towers.
Nearly 3,000 people died when four hijacked airliners were crashed into the World Trade Center in New York, the Pentagon and a field in Pennsylvania.
