Opening paragraphs

The Pentagon is the world's largest office building, six and a half million square feet, thirty thousand people, more than seventeen miles of corridors, but it was built with just three street doors, each one of them opening into a guarded pedestrian lobby.  I chose the southeast option, the main concourse entrance, the one nearest the Metro and the bus station, because it was the busiest and the most popular with civilian workers, and I wanted plenty of civilian workers around, preferably a whole long unending stream of them, for insurance purposes, mostly against getting shot on sight.  Arrests go bad all the time, sometimes accidentally, sometimes on purpose, so I wanted witnesses.  I wanted independent eyeballs on me, at least at the beginning.  I remember the date of course.  It was Tuesday, the eleventh of March, 1997, and it was the last day I walked into that place as a legal employee of the people who built it.
-Lee Child,  The Affair