For one generation it was the assassination of JFK...
For another generation it was man landing on the moon...
There is a moment in the global consciousness that people of a certain age can recall with total clarity years, now decades after the event.
For people of my age it was 9th September 2001.
It was early on a Tuesday morning in the United States, it was lunch time in London.
It is hard to recollect the Information Age that was around has at the beginning of the 21st Century. The Internet was not as prevalent, not the instant resource for news, and certainly not as fast and all-seeing and all-knowing as it is now.
We were sitting at out desks, eating lunch and catching up with the morning. I worked in a Regency style building in Central London at the time, lots of small interconnecting rooms over three or four floors of office. I remember one of my colleagues coming back from the shops and saying that they'd heard some people in the street saying that a plane had hit a building in New York. The instant verification from websites and Twitter wasn't the next call then. A few more colleagues came back from the shops, with bits of further reports - the World Trade Centre, a 747 plane...
Surely 747 couldn't be right? That would be a jumbo-jet, surely they meant a light aircraft?
News was slow to emerge. Websites crashed under traffic requests. We all got back to work, but the afternoon was constantly interrupted with updates and further new snippets.
My brother worked over in Canary Wharf and the buildings there were evacuated; several high profile London buildings were.
The evening papers were almost impossible to get hold of that night, everyone needed to know what had happened; although it wasn't until the following day that the full horror became apparent.