The mood of the early fund-raising events for Friends of the High Line was dreamy. What would the far West Side look like if 7 acres of open land became available for development?

Now that the question has an answer – in the form of a preliminary design by the firms Field Operations and Diller, Scofidio + Renfro, $51 million in city funds and a federal authorization to use the land – the prevailing outlook is different.

The 750 guests at the Friends of the High Line’s fifth annual summer benefit Wednesday were full of faith and confidence that big ideas in a big city can become a reality. The project is expected to break ground late this year.

The event honored three people who have helped the project along: the commissioner of city planning, Amanda Burden; the photographer who first documented the beauty and variety of the structure, Joel Sternfeld, and an executive at the Nature Conservancy and leader of the Rails-to-Trails Conservancy, Ed Norton, father of the actor Edward Norton.

“There’s nothing like the High Line anywhere in the world. It makes you fall in love with New York all over again,” Ms. Burden said.

Ms. Burden revels in the unexpected nature of the project. “New Yorkers have an idea of what a park should be. This is not that park,” Ms. Burden said.

While many have played a part, Mr. Sternfeld and others give the credit to the founders of Friends of the High Line, Robert Hammond and Joshua David.

“These are two artists who gave up their art to bring this project forward. They’re the real heroes of the High Line,” Mr. Sternfeld said.

Or as Mr. Norton the actor put it: “The left and right ventricles, the heart of this project, are Josh and Robert. They embody everything that is best about New York in terms of people who step forward selflessly. They will go down in history, uttered in the same breath as Jane Jacobs.”

Some clues to the duo’s success came from Mr. Hammond’s mom, Pat, a kitemaker and -collector who must have taught her son to keep his eye on the sky.

At Robert’s graduation from Princeton in 1993, for instance, Mrs. Hammond brought along 93 kites. At this week’s event, too, she handed out kites she had made, including one with a photograph of Robert at his second birthday party. That was when Robert was, according to his mom, “obsessed with trains, but just for a narrow time.” In the photograph, Robert poses with his birthday cake, in the shape of a train.

The new High Line is all about what kind of urban living space can take the place of trains. Robert’s father offered one possible explanation for his son’s interest in a redevelopment project.

“I made him take an architecture course,” Hall Hammond said.

Over the years, the crowd of supporters has grown – and grown up. Designers and architects signed on early, giving the organization a Prada and Theory chic. This year, other professionals were out in full force in their Ralph Lauren business suits and colorful Calypso dresses. It was a powerful and wealthy crowd that brought in an impressive $1 million.

Andre Balazs has plans to build one of his Standard Hotels straddling the High Line, so members of his staff, including Mike Mahony, had a table.

The event also attracted the visionary New Yorker Barbara Romer, who is leading the effort to build a Globe Theater on Governor’s Island. Other guests included Robert A.M. Stern, Moby, Terence Riley, Richard Meier, the Reverend Alford Sharpton, and Gifford Miller.

Guests were in awe of the High Line story.

“I think what I’m most impressed with is how an enormous, complex, urban development has moved so fast,” a real estate developer, Alf Naman, said.

A retired partner in the law firm King & Spalding, Jim Wildman, said: “It’s a terrific idea that’s actually going to happen and nobody is complaining about it.”

“This could be our generation’s Central Park,” Mr. Hammond said.

Mr. Norton the honoree spoke of the future. “Fifty years from now, New Yorkers will not regret what we did with the High Line,” he said.

Mr. Norton the actor, a downtown resident for 14 years, wasn’t thinking that far out. “If I stick one more tree on the roof, my co-op board will be very upset,” he said. “I can’t wait for the green space of the High Line.”