Along with the images of last week's unthinkable collapse of the World Trade Center towers, the consequences will stay with us for all time.
The scale of the loss is now clear. The scale of the clear up is there for all to see. The scale of the recovery needed by the population of Manhattan, New York, the US and around the world is slowly being revealed.
We must first, of course, hope that the world can negotiate this difficult situation without escalating retaliation into a yet greater catastrophe.
But beyond this, the profession has a major role to play in helping to deal with the loss, the clear up and the recovery. And the way that engineers in New York have already rolled up their sleeves, pulled together and got stuck in alongside the emergency professionals is fantastic to see - and does more to advertise the value of a civil engineering career than any trendy advertising campaign.
Descriptions from the scene by our reporters this week certainly reinforce the scale of the tragedy, and this information helps us come to terms with what happened.
As engineers we must also look forward. Certainly human tragedy on this scale cannot be ignored and we must take time to reflect. But we must also be the source of sensible, clear thought about the decisions made during the design process and on the potential consequences of the unthinkable.
The profession will no doubt spend much time examining what we might learn about the design of infrastructure in the future. And as is highlighted in the magazine this week, we must not be tempted to rush into making instant decisions.
However, it is the nature of what we do that such infrastructure disasters have to become massive learning grounds for the profession. Incidents like the 1968 Ronan Point collapse - albeit nowhere near the scale of last week - or the Gujarat earthquake in which tens of thousands were killed, prove that huge advances can be made in our design thinking.
We can also rest assured that every engineer now has a set of images, facts and figures ingrained in their minds to illustrate the potential consequences of failure. This will surely do more to engender good design thinking than any set of codes or standards - revised or otherwise.
But history shows that even after tragedies we do not always learn every lesson as well as we might. While it is inappropriate and probably grossly unfair at this point to suggest the twin towers could have been practically designed to survive last week's military style assault, we must not rule out an investigation into this issue.
The need to assess the risk of aircraft impact on high rise has been discussed for nearly 30 years and the public deserves to hear a reasoned discussion and explanation of the options and risks it faces when living or working in these structures.
And as the president of the ASCE said this week: 'The engineering profession has to be sure society understands these risks.'
So it is vital that we focus our efforts on the needs of society - explaining and reassuring that life can go on. But it is also vital that we do not let the huge human loss in Manhattan and the extreme circumstances of what happened hinder our learning.
Antony Oliver is editor of NCE