I remember in the days following the events of 9/11 the clear blue skies without the faintest con trails of aircraft as all flights in the US were cancelled. You don't know how accustomed you are to a sight until it is entirely gone. I remember the first sound of a flying machine I heard afterwards and how I paused, breath held, until it faded in the distance without impacting some building and exploding. I remember that sense of innocence lost (along with the general horror of those days), realizing we now knew a different way in which everyday objects could be used as manned missiles.
Here is a link to a commemoration beginning in New York City at 8:30 AM today: http://new.livestream.com/accounts/1378137/events/1174227
For all those suffering today as they remember the events of 2001, I stand with you and pray for you on this difficult day. You are not alone.