The following was from an email I sent a dear friend last year on Sept 12th after the attacks. As everyone, I'll never forget that day.
Manhattan was eerily calm and quiet last night and this morning. All the times I've been there with you were so very radically different from now. We walked up to Central Park from 51st last night at about 7:30pm and there were no cars, hardly any people, just a couple of lines of firetrucks waiting to go downtown for relief. West Drive (all roads in Central Park actually) were closed down and folks were just walking their pets and actually stopping and talking to each other in the middle of the streets.
I had went up yesterday morning for meetings in the Time & Life building and watched the towers burn on the bus trip in from Teterboro, NJ airport where the AOL plane lands. It goes through the Lincoln Tunnel and we were sitting there fixing to go through at about 9am. We made it onto the island, and had half a day of meetings before the started evacuating the buildings around Rockefeller Plaza.
Obviously I didn't get home last night and ended up rooming with another AOL-Virginia person who was up there. We took the Amtrak Accela back this morning. The walk down 7th avenue through Time Square was simply unbelievable. Our group of 8 folks going to catch the train were the ONLY people in the center island of Time Square when we were crossing. There should have been lines waiting for tickets to shows and the like! During the 17 block walk down at 8:30am we only had to stop once for crossing traffic. We saw less than 10 cabs and only a handful of cars. No honking horns, hardly any noise, everyone less rushed and even displaying "social graces" that I've never seen in NYC before. There were way less people walking than even any weekend we were in Manahattan.
Downtown DC was somber as well when we got in, though nothing like Manahattan. I don't know anyone personally that was caught in either attack.