Some time after the first WTC tower collapse, counterterrorism “tsar” Richard Clarke orders all landmark buildings and all federal buildings in the US evacuated. He also orders all harbors and borders closed. [Clarke, 2004, pp. 14-15] The Sears Tower in Chicago begins evacuation around 10:02 a.m. Other prominent buildings are slower to evacuate. [Ottawa Citizen, 9/11/2001]