Where was I? It seems everyone is answering this question.
I worked for Sun Microsytems at the time and was in the King and Queen building complex in Atlanta in a sales training class. There were no TVs, so we only go the news via cell phones and the Internet. But the Internet had ground to a halt.. As soon as it happened, I knew it was Bin Laden. I was convinced Bin Laden (not Iranian Hezbollah) was behind the Khobar Towers bombing, which killed five of my 71st Rescue Squadron mates in 1996. I felt it odd to be explaining Bin Laden (who I described that day as the closest thing to a James Bond super villain who actually existed on this earth), continuance of government, and SCATANA to my coworkers. It was like I was in on everything which was happening and everyone else was blind. Somewhere in there I called my Reserve unit in Alabama and let them know if they needed me I could be ready and down there in four hours.
At some point someone said Sun's New York sales office was in the World Trade Center (floors 25 and 26 of the South Tower, the second tower hit, and the first to collapse). That realization changed the dynamic of our class. Within about an hour we got word the entire Sun office evacuated after the North Tower was hit, and everyone in the office made it out safely. Crazily enough, we pressed on with our class. We wandered like zombies to HoneyBaked Ham for lunch, came back, and I presented my portion of the training class.
That evening, after a couple of Jack on the Rocks at Joey D's Oak Room with my colleagues, I drove home. On the drive, I called a former 71ster (Darryle Grimes) stationed at the Pentagon. He had been in the Pentagon during the attack, but was far enough away to not actually feel the impact. He told me the Pentagon had gone to 24 hours operations and he had to be back there in a about an hour.
The second thing I remember is I was not able to sleep that night. That is only one of two nights in my adult life I was not able to sleep at all.