All of a sudden, the density of the air is no longer the same. The murmur of the city dissolves into a squal whose chill and power I no longer feel.

With the grace of a dancer, Philippe Petit, floats 20 feet above the ground across a high wire. At 74 years old, a mesmerizing display of balance and defiance. You remember me. With with his good friend Sting, serenading his feet. It's been 50 years since Petit's death-defying walk between the Twin Towers, a dot appearing in the sky, capturing the world's imagination. Here at St. John's Cathedral in New York City, surrounded by hundreds of adoring fans, he's celebrating his place in history.

It's a lifetime, 50 years, and yet it's nothing. I look, I see all the detail of my walk then as if it were yesterday.

Petit is one of the world's most renowned performance artists, known for his daring walks on wires hundreds of feet above the ground without any safety net.

What's your relationship with the wire?

I spend a of time, trying to create a walk in which my whole mind and body almost secretly communicate with the cable. So it's a very intimate personal relationship that I created with the apparent inanimate piece of steel. But to me, it's really vibrant, full of life.

The Frenchman burst onto the scene in 1971, shocking the crowds in Paris by walking between the spires of the Notre-Dame Cathedral. Two years later, he reappeared, this time on a wire strung between two pylons at the Sydney Harbor Bridge. But it was his breathtaking walk between the Twin Towers in 1974 that sealed his celebrity, chronicled in the Oscar-winning documentary Man on Wire.

There is somebody out there in a tightrope walk between the two towers of the World Trade Center, right at the tiffy top.

And the feature film The Walk, starring Joseph Gordon-Levitt. The renegade artist, boasting of the illegal nature of his walks.

How many times do you think you've been arrested?

Actually, I know because I was counting. I have been arrested more than 500 times in my life, but not for a bad thing, for artistic crimes. Mati, are we going good?

Nightline got rare behind the scenes access as the artist prepared to commemorate his most infamous walk.

What's the elevation Again, again?

20 feet.

20 feet.

An inside look at his private training grounds.

I open the door and I invite people to peek into my world, which is a world of poetry, a world of calm and his intense process. Everything is to scale. The mast are 20 feet high.

Most people will not risk their lives on a wire, but they wonder, where do you put the fear?

There is no fear. There is a certain childlike impatience. I We are the performance, and I am solid. I am in control. There is no fear.

We visited Petit on a hot summer's day at his home in upstate New York, just in time for his daily regimen.

At And so how do you train now?

I have four high wires, low, medium, high. I dedicate myself three hours a day, an hour and a half of warmup and juggling, and an hour and a half on the wire.

To the music of Henry Purcell, pateek glides across the wire, unbothered by gravity or the effects of aging.

I have no respect for age. I don't recognize age. I feel I am in complete control role of my art, and I am more solid on the wire and probably more majestic than when I was a rebellious 18 years old trying to prove things.

Petit grew up outside of Paris and quickly found himself attracted to the world of aerial arts.

I love the fact that to look at a wire walker, you have to look up to the sky. And when you look up, you start flying. You're being inspired.

What was the first spark as the young young, rebellious teenager that drew you into it?

I'm glad you use the word rebellion because it's really what characterized the beginning of my young life. I remember that I start climbing. Many kids like to climb. And I think climbing is a way to separate yourself from the world below, and it's an act of rebellion. So I spent my childhood climbing.

The act of rebellion driving his desire to reach new heights, spending months meticulously is early planning his most famous caper, his team pretending to be part of a construction crew to gain access to the Twin Towers.

I want to show you this. What goes through your mind when you see this?

It's really bringing me back to the feeling that morning at 07:00 AM, 07:15, I step on the wire. The rigging was really not great. I had not been able to check the other side, which I always do before a performance. So I was very hesitant and delicate on the first crossing. But then in the middle of the crossing, I start smiling because I knew it was not a disaster.

Hardly a disaster. He became comfortable enough to cross back and forth eight times while balancing 1,350 feet above the ground.

So it was for the sake of beauty or art. It was for no reason because I just feel it. I say, Oh, that would be fantastic. Why there?

When you stepped off the wire 50 years ago, you were once again arrested. Yes.

It was illegal, yes, but I became instantly a New York celebrity.

The 24-year-old was charged with trespassing and disorderly conduct, but the charges, dismissed.

What I want to do is to feel like a bird all my life, to go above the ground.

On the condition that Petit put on a free performance in Central Park. The connection, personal for Petit. Nightline spoke with him after the World Trade Center was My first thought at the loss of life and at the destroying of those two giants was unbelief, disbelief, and of course, sorrow for the lost human life. The legacy of the tower and his iconic walk, front and center in his anniversary performance.

When you lose a loved one, of course, tears come in and you have to grieve, but also sometimes smile and joy and laughter love to love to love to love to love the departed in the glory of their life. So I think it is the same.

A hush falls over the packed crowd as the show begins. Comprised of 19 distinct scenes, the performance, named Towering embodies Petit's journey to his historic walk, reenacted by dancers and musicians. As as well as the main star, his feelings of victory, and the moment he was confronted by NYPD. As the show is about to close, a special surprise, the premiere of Sting's new song, Let the Great World Spin.

I've known Philippe since 1980, and he took me to the top of the tower, and he told me the story actually looking down, so I got vertigo. It was easy to write that song because I've lived it with him.

To me, a good performance is one where you give yourself 100% and you get a response from the audience. To me, it happened tonight, but what do you think?

Exactly what he said.

I agree.

It's clear that this show is far from the end of Petit's high-flying career.

You said that you will never retire.

My age is old, but my mind is very young and aggressive and rebellious like I was three years old. I hope to continue to tour the world with my heart. This is my wish.