For 10 years, I haven’t been able to think or write about the Twin Towers without tears welling.

It just happens.

That Tuesday morning’s crystal-clear blue sky made it easy to see, and riveted all of us who watched the towers burn and die.

I was getting our youngest son ready for his first day of school. The TV was on Fox 5’s morning show when, at 8:48 a.m., Dick Oliver, who was at City Hall reporting on the New York state primary, said a plane may have hit a World Trade Tower and showed smoke pouring from its top.

My first thoughts were for Larry Silverstein, a gentleman who is the epitome of happiness and optimism. He had “lusted” for the World Trade Center and signed a 99-year lease to operate it, at a ceremony on July 24.

Silverstein Properties had moved into temporary offices on the 88th floor of the North Tower. There was no answer at either of the offices, nor on his cell.

I frantically called his publicist, Howard Rubenstein, and blurted the news, starting a long and terrible decade.

His early meeting with the Port Authority had been canceled, and Silverstein went to his dermatologist, so neither he nor his two children were inside when the first plane slammed into the tower.

But former FBI special agent and terrorist expert John O’Neill (who had joined the company as head of security on Aug. 23), Director of Operations John Griffin, Fire Safety Director James Corrigan and Chief Engineer Charles Magee all perished.

“We lost four people, and it’s a miracle that we didn’t lose more, and it’s an absolute miracle that God spared some and not others,” Silverstein said later.

“It’s pretty tough to understand why and how. It makes sleeping at night difficult, and it’s so depressing — and you have to steel yourself each day — and it’s the magnitude of the event on our lives”

When I walked through Ground Zero in late September a decade ago, the 16 acres of raw devastation were overpowering, with acrid smoke trails rising as firefighters, and rescue and construction workers, meticulously picked through the ragged piles for victims.

On a nearby roof was a letter addressed to developer Harry Macklowe from a Twin Towers law firm. I left it but pocketed pieces of glass and chips of concrete.

In February 1993, I had accompanied then-Borough President Ruth Messinger on a tour of the bomb-blasted garage. We followed in shock as building manager Charles Maikish led us through the bowels of the complex.

On the night of the bombing he had gotten the lights turned on in the towers to send a message to the terrorists. They got the message, and they came back eight years later to finish the job.

Silverstein vowed to rebuild the Trade Center “for our children and our grandchildren.” By October 2001, architect David Childs had designed a new, 52-story 7 WTC with 1.7 million square feet, which was completed in May 2006.

But it took nine years of pushing by Silverstein, the governors, the mayor, the media — including Post colleague Steve Cuozzo, who wrote about the passing time and wasted efforts — before Port Authority Executive Director Chris Ward ensured the rest of the development was on track.

When it opens in late 2013, the new 104-story 1 World Trade Center, owned by the Port Authority and the Durst Organization, will have 3 million square feet and rise to 1,776 feet at the top of its antenna. Silverstein’s new 4 WTC will encompass 2.3 million square feet in 72 stories that reach 977 feet — the site’s shortest office tower. His 3 WTC will be 80 stories, topping out at 1,170 feet and include five trading floors in its 2.8 million square feet.

The slanted top of Silverstein’s tallest, 2 WTC, will eventually reach 1,270 feet and have 79 stories containing 2.3 million square feet. Australia-based Westfield Group will also be developing more than 360,000 square feet of retail and restaurants.

At the time the Port Authority decided to lease out the Trade Center, the six-building complex had more than 10.5 million square feet of offices, a hotel and 300,000 feet of retail space. The Twin Towers alone had 4,761,416 square feet each, and each floor covered an acre.

On the 10th anniversary of Sept. 11, I will be on a plane and worried about flying because terrorists don’t want to forget.

Between the Bricks will return Sept. 28.

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