An impromptu memorial grows in the heart of Somerville’s Davis Square in the days after the terrorist attacks of Sept. 11, 2001. (Photo: BostonTx)

Cambridge Day is part of a project called Voices of MainStreet — a weekly, nationwide Q&A in which editors at the money and lifestyle site MainStreet.com ask questions and bloggers answer them. For this entry, we took the option of talking about the terrorist attacks of Sept. 11, 2001, and our reactions to it.

Right after 9/11 there were a couple of things that hit me pretty hard.

One was on the trip over the Charles River from Cambridge to my job at the Boston Herald. Every day I would stare hard at the Boston skyline as I approached, often until the T brought me among them — a set of buildings smaller and shorter and less impressive and meaningful than those of New York, which drew the misplaced zeal of madmen who used planes as bombs and office workers as targets.

I was being appreciative not just that my little skyline was intact, but for the life of my brother.

He’d woken me up Sept. 11. Since my workdays only started at 3 p.m., I slept disgracefully late, and it was his call that woke me up and his strange greeting that, well, really woke me up. He said something along the lines of: “I’m alive.”

See, he’d flown out of Boston that morning on the way to Las Vegas with of course a full tank of jet fuel at about the same time as the terrorists who hijacked airplanes with equally full tanks of jet fuel, the better to incinerate the innocent when their planes flew into the World Trade Center and Pentagon. What saved my brother was that the terrorists had trained to fly (but not land) on aircraft made by Boeing; he had flown out that morning on planes made by Airbus. His plane hadn’t been flown into a building or a field near Shanksville, Pa., but had landed as part of the national no-fly order and stranded him in Kansas City, which he made his way out of via an absurd road trip shared with a stranger who hadn’t been on the same plane but was now in the same boat.

His call compelled me to the television in the house we shared, where I saw that notorious footage for the first time — the billowing smoke, the falling people — and then to bolt for my clothes, our front door, the T, a taxi when mass transit bogged down and finally by foot for my newsroom when street traffic also got clogged by panicked people in clumsy cars, everyone watching the skies and also, if you remember, seeing each other for real for probably the first time.

By the time I reached the Herald, those assembled had already put out an extra edition about the attack. I wanted to help. I wanted to do something. But in fact I sat around being useless until 3 p.m., when my work hours started pretty much as usual and I did what pretty much amounted to the typical workday.

At the end of it, I rode home on the T toward the Cambridge skyline, which is even lower and less significant than that of Boston, when compared with Manhattan, and slept. And went to work the next day, appreciating the Boston skyline, and did the same the next day and the next and the next.

I also went the opposite direction, walking up into Somerville (which has an even less significant skyline than Cambridge, in fact, barely a skyline at all), and found people gathering nightly in the heart of Davis Square around a giant concrete and metal compass planted in the center of a traffic circle in 1983 to mark the area’s hundred-year history. They came and cried and sang and left candles and cards and notes and posters (of poems and thoughts and pleas) and even the occasional inevitable American flag night after night until the compass was covered completely, and then surrounded by more posters and printouts and paintings, growing and growing and being replenished and renewed and replaced until it felt like the memorial would never end.

This is the other thing that hit me hard.

I understood that those people needed to do something, just like I’d raced to the Herald to do something. To help when you couldn’t help.

Over time I started forgetting to stare hard at the Boston skyline and appreciate it still having everything in it, and over time the Davis Square memorial ebbed and was cleaned away, and now there’s a concrete and metal addition to the compass — a memorial to the memorial, essentially, by way of recognizing what happened Sept. 11, 2001, in the form of flattened, stylized twin towers that, unfortunately, aren’t reminiscent of the twin towers at all and fail to capture in the least the power and beauty of the simple, homespun, heartfelt items they replaced, the things that showed people’s hearts broke alone and healed when put together.

That’s the nature of things: The very special comes to seem normal after a while, especially when you fail to notice what made things special in the first place.

But for a while, the gleaming, mirrored John Hancock Building jutting into the sky over Boston was the most beautiful thing I’d ever seen, and so was the junk people left uselessly on the ground in the center of a traffic circle. The one thing that never got old or wore off? Living with my brother in Cambridge, which I got to do because he lived through 9/11.