A New Jersey teen captivated by 1 World Trade Center sneaked out of his home in the dead of night, got past a wall of security — and a sleeping guard — and made it all the way up to the spire, The Post has learned.

Scrawny, 16-year-old Justin Casquejo crawled through a hole in a Ground Zero fence at about 4 a.m. Sunday and got a lift up the tower from a clueless union elevator operator, even though he had no ID.

He was dropped off on the 88th floor and hiked the stairs up to the 104th floor — where a guard assigned to protect the top of the world’s biggest terror target was sound asleep.

That guard has since been fired.

Casquejo told cops he then climbed up to the roof and made it up to the antenna.

After spending two glorious hours atop the nation’s tallest building snapping photos, the young daredevil was finally caught by a construction worker as he made his way back down.

“He came here and he ran hog wild,” said a stunned WTC worker.

Casquejo, who lives in Weehawken, NJ, laughed the whole thing off Wednesday afternoon when The Post asked him about his escapade.

“Ha ha, oh yeah, that. Right. I would really love to talk to you guys because I have a lot that I want to say about it,” he said. “I was told that I just can’t [talk] without permission.”

But he summed up his adventure in a one-word tweet: “Inspired.”

Casquejo has long been a WTC buff. His Facebook page features photos of him posing with the building in the background.

When cops questioned him, he bragged that he had little trouble getting past security at a building that was supposed to be cloaked in a “ring of steel.”

“I walked around the construction site and figured out how to access the Freedom Tower rooftop,” he said, according to court papers.

Law-enforcement sources said Casquejo got into the heavily guarded site like a kid sneaking into an abandoned warehouse — though a gap in a barbed-wire fence.

“He’s a skinny kid who got through a skinny hole,” a source said.

The elevator operator who asked no questions while taking him skyward has since been reassigned — but got to keep his job because of his hardhat union. But the guard who was snoozing on the top floor wasn’t as lucky — he was immediately fired.

Casquejo faces a charge of misdemeanor trespassing, but his adventure is an epic failure of at least four layers of security at the WTC site.

The Port Authority Police Department, the NYPD and a private security company patrol the building perimeter. Another private company secures the interior.

None of them would comment.

Additional reporting by Rebecca Rosenberg and Antonio Antenucci