It started as a gorgeous late-summer morning in New York City. Then everything went straight to hell.

Where were you when you knew?

Twenty-five years have passed as if in a heartbeat. On the morning of Sept. 11, 2001, I was sitting on the deck atop my Brooklyn brownstone with stunning views of lower Manhattan, preparing to take my daughter to her first day of preschool when a small plane appeared to fly into the north tower of the World Trade Center. Or so we thought.

Minutes later, a second, deafening crash. A second plane, a jetliner, joined the first, which turned out to be another jumbo jet, and struck the south tower, setting the two buildings on fire, high above the ground. A sick feeling hit the pit of the stomach as everyone in the nation and around the world, fixated on the twin, burning buildings, whether watching on TV or in person, simultaneously came to the same, horrifying realization: Suddenly, we all knew this was no accident. America was under attack.

And nothing would ever again be the same.

It goes without saying, preschool didn’t happen.

The rest of the day unfolded as if in a nightmare. Before our eyes, the grand and imposing towers fell, one by one, brought to their knees by the fires of hell.

A smoke cloud billowed over Brooklyn, blotting out the brilliant sunshine and spewing ash, singed paper, the mangled detritus of two, destroyed buildings, onto our deck, covering it like a blanket of snow. We had no clue that the ash, toxic and deadly, would sicken countless people, killing untold numbers for years to come.

Then reports dripped of a hit on the Pentagon. A plane down in Shanksville, Pennsylvania.

Where would it end? Would it?

I walked down the street, past a subway stop bearing pictures of missing locals, their eyes searching, begging for help. I passed a man. He was sobbing.

I joined him.

Over the next few days, I ventured daily to Ground Zero. Searching, hoping, praying, to find even one survivor. Something that would bring hope. Joining rescue workers, I searched hospitals, a makeshift morgue, the wreckage itself. I stood near the pile that used to be the trade center, watching men combing through the rubble, bucketful by bucketful. The silence spoke volumes.

No one could survive this.

So many funerals. An endless procession of death. Maintenance workers. Office workers. Cops and firefighters. First responders. Christians and Jews. Muslims and atheists. Hindus and Buddhists. All innocents. All gone, simply because, on this gorgeous late-summer morning, they showed up for work.

Yet amid the ugliness, I witnessed beauty. Never before had I seen the people of my city, my country and beyond so united. We were defiant in the face of evil and determined not to let it break us. Republicans, Democrats, nonvoters. Islamic militants were determined to destroy the American way of life by crippling its financial center. But the people united and said, in unison, “Hell no!” We were one.

Tragically, it wouldn’t last.

Twenty-five years after 9/11, I barely recognize my city, my country. This is no longer the world that hugged battered Americans close.

A quarter century ago, we knew who the enemy was. Now, according to a disturbing new survey, two-thirds of American Middle East studies professors say college students can’t identify who attacked the United States on 9/11 or why.

Maybe that has to do with the woke notions infesting education. In some districts, educators refuse to call al-Qaeda butchers “terrorists.” In others, they excuse hatred of America with rampant Islamophobia, while failing to even mention that antisemitic acts have skyrocketed globally.

It doesn’t help that around the country, leftist politicians campaign and win on platforms heavy with America-hatred and 9/11 denial. The wife of New York City’s own mayor, Zohran Mamdani, shows a disturbing level of sympathy to terrorists on her social media, while Hizzoner surrounds himself with an administration, friends and advisers who feel the same way.

On Friday, we honor the nearly 3,000 souls murdered on that awful day 25 years ago. I add my name to the more than 100,000 people who’ve signed a petition imploring the mayor to stay away from Ground Zero on that solemn day.

This is a day for remembrance and reflection, not leftist politics and division. It is a day for healing.

Never forget.