9:59AM - South Tower collapses. In the past nine minutes I managed to reach my office building, where I saw a concerned concierge from whom I managed to get a permission to go to our rooftop.  The two slow elevators that we had in the building again where somewhere in a space continuum. I used the stairs to get to our office on the 7th floor where I told my colleagues that I'm heading to the rooftop.

Then I climbed another fourteen or so floors to the rooftop. With a heavy bag over my shoulder, and summer-like temperature outside it took just a few floors for me to start sweating. I could only imagine how inhumanly hard it was for FDNY firefighters equipped in full gear to climb endless stairs of World Trade Center skyscrapers.