I lived on 91st St and Lexington Avenue, in a 4th floor walk-up apartment a block from both the renowned 92nd Street Y and the bus I took to Columbia each weekday morning. I liked my route. An M bus snaked north into Spanish Harlem and then west along Central Park's top edge before turning north again and toward my stop at 116th and Amsterdam.

I loved watching the City go by: power commuters pounding the pavement with a bagel in one hand and a phone in the other; nannies strolling children to school or the playground; the bodegas raising their steel bar doors; neighbors greeting each other; vendors selling Greek paper cups of coffee; the regulars hop on and off the bus.

That Tuesday morning, I felt like a regular myself. I was seated on the left side of the bus, in a single seat if I recall, and it was a beautiful day. Blue skies, leaves starting to change colors, a nascent fall crispness in the air. I got to work just before 9:00 am. Our permanent offices were in Hamilton Hall, but renovations meant we were in a temporary building then, two to an office. I was sharing space with one of my favorite colleagues, Peter.

I don't remember if I'd heard the news before I arrived-cellphones then were flip, data-free ones-but as soon as I walked in, I knew something was wrong. We all gathered around a screen and watched as the second plane slammed into the South Tower of the World Trade Center. I remember gasping, looking around, everyone in disbelief. Classes had just begun, new student energy was still buzzing around campus. It was a perfect New York day. I'd just felt like a regular.

It was all utterly dissonant.

And then the South Tower collapsed. Just 56 minutes after being hit. A 56 minutes that felt at once glacial and like warp speed. I can't adequately describe what it was like to watch that mighty structure crumble in on itself. To watch people jumping from windows, to watch the smoke and fire juxtaposed against the blue sky. To watch replay of those planes flying so purposefully and directly into a monument to a vibrant, wholly unique city.

The North Tower collapsed just 29 minutes later. Meanwhile, the Pentagon was hit. And some spectacularly brave passengers forced a fourth plane to crash land in Pennsylvania instead of into another DC target.

And still we gasped, mouths agape, shellshocked expressions on our faces. Few people could get a phone line; those who did started phone trees, and family and friends called other family and friends and even strangers to let those loved ones know each of us was alright. If memory serves, my mother was one of those called.

Some parts of my memory of that day are so clear but others are as hazy. I don't remember anything of the sounds, but I do remember the smells.

My friend, Jessica, and I walked home together that evening. Public transportation was at a standstill, and as we picked our way south and through Central Park and back to the East Side, I noticed shellshocked faces everywhere, all of us woozy with stupefaction but kept from going completely numb by the smell.

If you looked south down any of New York's avenues, those sturdy aortic drags connecting the bottom of Manhattan to the top, you'd see a thick gray shroud butting up against whatever blue was left in the sky. It was a shroud of the thickest, densest weave, and its seismic perfume reached up and up and up more than a hundred blocks right into our nostrils and windows and doors and bedrooms.

The gray shroud reached like hands towards the living, reminding us for days after the Towers fell and thousands died and people were so brave and unified and generous just what had been forced onto the City.

I remember being in bed that night, safe and wrapped in clean blankets, and thinking "it's in here with me, that smell and all the particulate debris it carried up here in its wake." It was an unbelievably strange sensation.

Perhaps you lived in New York too, or read about everything that day and afterwards. If so, you know what strength and spirit and resilience the City showed in response to the grotesqueness foisted on it.

I remember making donations at our neighborhood fire station. Remember seeing posters and photographs of missing loved ones. Remember the flags beating proudly in the wind. Remember the smell finally dissipating.

9/11 didn't terrorize me or even mark me much. But that's because I was a lucky one (and because I'm white), and for that I am ever grateful. I didn't know Tom then but he worked in DC and remembers where he was when he heard that the Pentagon had been hit. You can still see the differential colors in the Pentagon's west side: the gray of the original stone versus the gray of the stones used to repair the gaping wound left by the hijacked airplane. I notice it every time I drive by.