People say this is an event where you always remember where you were when you heard it had happened. It was such an enormous thing if you were old enough how could you forget? There are other dates which are the same, the day JFK was assassinated, the day Diana died, and there are a few others.
This is my remembrance of hearing about 9/11:
My sister-in-law and I had dropped our children off at infant school on their 4th day of starting in the infants, her son and my daughter who are only one month apart in age, and were walking back to her house when one of her neighbours passed us and told us to put the news on when we got back as one of the twin towers in America had been hit by an aeroplane and was on fire. We didn't really know what the twin towers were at that time and just thought 'Oh how awful', but didn't put the tv on as we were busy talking about our children and other things. I didn't see what had happened till the afternoon when I got back to my house after picking up my daughter at lunchtime, by then the second tower had been hit, too. I remember being gobsmacked when I realised what a huge thing it was that had happened and couldn't stop watching things unfold for hours. I felt as though it had put a sort of blight on her first week of starting school as it was something that would always be associated with it.
Another thing about it is not just remembering where you were when it happened but that everyone, even here in the UK, seemed to know someone who was in one of the towers at the time, or had been within a few months, or knew someone who knew someone, so it kind of touched us all. For instance a close friend's brother had been in one of the towers 2 weeks previously, and we heard many other people who knew of friends, family or acquaintances who had been there recently and were so relieved they were safe.
Many believe the world lost something that day which changed everything. Today is a sad day for all.