“I lived in the house for a summer in 1976 and 1977 — it was our summer house,” said Ms. Aezen, 42, of Manhattan. “I was watching CNN one night a while ago and I heard this was happening. I had to come down. I’m just so glad it’s being saved.”

The Lieb House, a beach cottage designed by a prominent Philadelphia architect that has been widely studied as a model of modernist architecture, was nearly torn down. Instead, on Friday, the house continued its unusual interstate journey, plodding up the East River on a barge, destined for a new resting place in Glen Cove on the North Shore of Long Island.The spectacle attracted a throng of about 150 onlookers to the third floor of Pier 17 at South Street Seaport, including the 83-year-old architect, Robert Venturi, who designed the house in 1969 for Nathaniel and Judy Lieb. The Liebs had it built near the northern tip of Long Beach Island on the Jersey Shore. The current owner of the property planned to demolish the structure, prompting the unusual rescue effort, which involved selling the house to an owner willing to relocate it.

Standing next to his wife, Mr. Venturi ignored the tangle of microphones and cameras thrust in his direction at the seaport, and applauded and waved with a weak smile as the 1,500-square-foot house and the barge carrying it came into view, wending its way northward propelled by a tugboat and trailed by a helicopter.The new owners of the structure, Deborah Sarnoff and her husband Robert Gotkin, stood a few yards away from Mr. Venturi and watched nervously as their new guest cottage sailed by. They live in another Venturi-designed home, and are paying the moving costs, which are somewhere in the low six figures.

Students, architects and friends hung over the pier rail to captured the moment with cameras, and watched through binoculars as the house and barge faded into the distance after passing beneath the Brooklyn and Williamsburg Bridges.”I had to come,” said Yoshi Tsukamoto, 43, a Tokyo-based architect, who learned about the move during a visit. “Venturi is very famous. I’ve seen the Lieb House published in magazines. I’m so much influenced by him. This is once in a lifetime — something very special.”

Michael Blasberg, a freelance architect with the Manhattan-based firm of Weiss-Manfredi, said he had been following Venturi’s work since college. “I used to make pilgrimages to see his buildings,” said Mr. Blasberg, 61. “I’d rent cars. So I saw this house in New Jersey. I’m a little nostalgic about being here.”

Fred Adelson, an art professor at Rowan University in Glassboro, N.J., who got up before dawn to make it to Pier 17 in time for the float-by, said he had been preparing to write an article about the 40th anniversary of the Lieb House when rumors started circulating that it might be destroyed.”This was a major monument in New Jersey architecture,” he said. “New Jersey’s loss is New York’s gain. The important thing is that it’s now getting the attention it deserves.”

The house was expected to arrive in Glen Cove around midday Friday and be placed on pilings on its new site in the afternoon.