Chicago Sep 10-14, 2001 (9/11 occurred during this one, smallest one, perhaps last public one)
Kent was here for this one. He got one of the special flights home. Other's had to rent cars to get home. I remember that the NOLA guys had to drive all the way down to New Orleans.
9/11 was a Tuesday. I was teaching with Kent, and the students were busy coding and learning TDD. My wife was helping out. She whispered in my ear that planes had crashed into building in NYC. Someone set up a TV in an office. and we watched the towers fall. The students all had network access and had seen the news. We made an announcement, but they knew already. They just put their heads down and _worked_. God bless them all (and I'm an atheist), they worked _hard_ that week. There was a minute of silence declared on Thursday (IIRC) and we all went outside and stared at the all too clear skies in silence.
Kent stayed at my house the night before he went home. We drank brandy and talked little. He left early. I still have the thank-you note he left. One does not forget things like this.