Twin towers for me too and also the Tsunami ............
I watched the second tower being hit live on the TV at work, it was like something out of a movie. I actually travelled to New York a few weeks later and came across the devastation myself ..... the remnants of the towers were still smoking and the surfaces of the surrounding roads were missing, baring the infrastructure of steaming pipeworks.
I watched very litttle news in 2004 and unbelievably didn't hear about the Tsunami for 3 days but after that I was glued to every bit of news............ what a terrible natural disaster