Back in 2001, I worked at the National Audubon Society, about a block from the White House, and across the street from the World Bank and the International Monetary Fund.
On a coffee run down the hall, I came into the kitchen and about 10 folks were in there watching the news on TV. Someone said an airplane had hit the World Trade Center. Assuming it was a small two-seater propeller airplane, I said the same thing had occurred to the Empire State Building back in 1945.
"Was it a 747?" one of my coworkers asked?
"Was it TWO 747's?" asked another.