Fourteen years ago, it was such an abominable outrage that is was visible from outer space.
And since that day, over 1400 of the first responders who ran to help and stayed in the aftermath have died of 9/11-related respiratory disease and cancers linked to the toxic environment that they worked in.
The death toll from 9/11 continues to rise. The numbers are growing.
These are some of the faces.
343 Firefighters killed that day. More dying now from the after-effects.
71 police officers from ten different agencies killed on that day. Over 160 dead now.
Remember the heroes. When thousands were running out, they were the ones running in and remaining afterwards to put things right. And they paid a heavy price indeed.