With my parent's generation, it's more like "Where were you on the day JFK was shot?"
My generation? 9/11, without a doubt.
I can't remember a lot of things. I probably couldn't tell you what I did last week, let alone twelve years ago. But I can tell you exactly what I was doing that day, and how events unfolded. On this day I always remind my kids (who were too young to remember) what happened. I tell them the story.
I will never forget. Ever.