A little more than an hour after dawn broke over Manhattan, an elfin man stood precariously on the edge of the south tower of the World Trade Center. Dressed in a black V-neck sweater, black pants and thin black slippers, 24-year-old Philippe Petit stepped off the 110-story building and tiptoed onto the sky.

With his hands clutching a large balancing pole and toes gripping a taut steel cable, the daring French aerialist began a death-defying 140-foot walk to the building’s northern twin with no harness, no safety net. The only thing underneath Petit was certain death as he walked between the two tallest skyscrapers in the world.

A quarter-mile below on the streets of lower Manhattan, New Yorkers craned their necks skyward toward the heavens and strained to see the black speck silhouetted against the gray morning sky. To the anxious crowd, the daredevil appeared to be walking on air. Petit could hear the blare of sirens and the murmur of the ant-like figures below his feet grow as news of his stunt spread.

For Petit, each step fulfilled a dream first hatched in the waiting room of a Parisian dentist more than six years before.

Barely 18 years old in the winter of 1968, Petit had already decided to move beyond his street-juggling act to become a “high wire artist supreme.” As he scanned a French newspaper while waiting in the dank dentist’s office, the teenager’s eyes lit up at an illustration showing an outline of the Eiffel Tower superimposed on the architectural models of the proposed Twin Towers for what the newspaper erroneously called the “Trade World Center” of New York.

Taking a pencil from behind his ear, Petit drew a wire between the roofs of the matching skyscrapers that were to be the tallest in the world. Ignoring his painful cavities, Petit tore the illustration from the newspaper, bolted from the office and filed it inside a large red box stored underneath his bed that was labeled “Projects.”

The budding aerialist began to perform on some of the world’s most iconic stages—completing high-wire walks between the towers of the Notre Dame Cathedral in Paris in June 1971 and the pylons of the Sydney Harbor Bridge two years later—but the Twin Towers continued to have a magnetic hold on him.

Petit recalled in his memoir To Reach the Clouds that he was overwhelmed the first time he saw the towers, partially occupied but still not complete, in early 1974.

“The volume of the towers, their size, screams one word at me, etches it into my skin as I pause atop the stairs, holding on to the railing: Impossible!” For nearly an hour, he scaled the staircase of one of the towers before reaching its deserted summit. After surveying the rooftop, a new thought popped to mind: “Impossible, yes, so let’s get to work.”

Like a bank robber plotting an elaborate heist, the obsessive Petit staked out the World Trade Center. On more than 200 reconnaissance missions to the Twin Towers, he meticulously studied how office workers entered and exited the buildings. He noted the colors of the helmets worn by the construction workers and the tools they carried. He watched how delivery vans entered and exited the subterranean garage and rented a surveyor’s wheel from a hardware store to precisely measure the distance between the skyscrapers.

On nearly every trip, he eluded the guards and snuck onto the rooftops to scout locations for securing his cables. He took a helicopter ride to view the towers from above and even posed as a journalist from an architecture magazine to interview construction workers on top of the Twin Towers while his friends snapped photographs of the rooftops. On trips back to France, Petit built wooden models of the World Trade Center and practiced on a wire that corresponded exactly to the distance between the two towers.

Finally, on August 6, 1974, Petit was ready to implement his covert operation to pull off the illicit walk. That afternoon, Petit and a handful of accomplices loaded their supplies into a van and drove to the World Trade Center. Disguised as construction workers and carrying fake identification cards from the faux Fisher Industrial Fence Co., Petit and two cohorts passed through security and transported hundreds of pounds of cable up the freight elevator.

Another pair of accomplices dressed as office workers and entered the north tower with a blueprint tube with a crossbow inside. Roving security guards caused both teams to hide for hours upon end, but after dark they reached the roofs of the towers. The team on the north tower shot an arrow carrying a cord across the abyss to the south tower and then passed heavier lines and eventually a steel cable.

By 7 a.m., the work to tighten the cable had been completed and Petit stepped out high above Gotham. A few minutes into the walk, policemen arrived on the rooftop but Petit only laughed and smiled. He knew they were powerless to do anything until the walk ended—one way or another.

The policemen could only lean against the girders and watch with everyone else as the lithe acrobat made eight trips across the wire, even kneeling down at times without losing his balance. Finally, after 45 minutes, Petit returned to solid ground.

The policemen immediately handcuffed the aerialist and read him his Miranda rights. After undergoing a psychiatric examination at a local hospital, Petit was booked for disorderly conduct and criminal trespassing. Under details of the complaint, an officer wrote only: “Man on Wire.” That afternoon, Manhattan’s district attorney dropped all charges in return for a free aerial performance in Central Park.

“My punishment is the most beautiful punishment I could have received,” the daredevil told reporters. When asked why he attempted the walk, he said, “If I see three oranges, I have to juggle. And if I see two towers, I have to walk.”

Petit instantly became a folk hero. Upon his release, spectators cheered and policemen asked him for autographs. Time magazine called the high-wire act the “artistic crime of the century.” Even the owners of the World Trade Center forgave Petit and gave him a lifetime pass to the observation deck.