The new plan — which comes after months of contentious negotiations between designers Daniel Libeskind and David Childs — retains many elements of Libeskind's original plan but appears to smooth out many of its most angular elements.
At a news conference to unveil the design, Childs said the tower must be "simple and pure in its form, a memorable form that will reclaim the resilience and the spirit of our democracy."
Mayor Michael Bloomberg said the tower — which officials hope will be the world's tallest — would "dramatically reclaim a part of the New York City skyline that was lost on 9-11."
"This is a wonderful day, not just for New York, but for America," said Bloomberg, who appeared with the architects and Gov. George Pataki to unveil the new design.
The cost is estimated at $1.5 billion, said Charles Gargano, vice chairman of the Port Authority of New York and New Jersey, the public agency that owns the site.
Gargano said the Port Authority, once headquartered in the World Trade Center, plans to occupy one-third of the building's office space. The governor's Manhattan offices will also be located in the tower.
The building is to be put up on the northwest part off the World Trade Center site, not on the footprint of the vanished towers.
The plan calls for a cable suspension structure that creates an open area above the building's 70 floors of office space, and houses windmills to generate energy. The windmills could provide 20 percent of the building's energy.
Childs likened the suspension elements of the new design to the Brooklyn Bridge, with the bottom of the building "torqued or twisted."
Trade center leaseholder Larry Silverstein, who brought Childs into the project, speaks passionately about the tower, reports WCBS-AM's Sean Adams.
"What we see today is, in my judgment, beautiful. It's spectacular; it is also very practical," Silverstein said.
He has promised to build one new skyscraper at the site each year after the expected completion of the Freedom Tower in 2009, finishing the five-building complex in 2013.
The new design retains an important part of Libeskind's original concept, a 276-foot spire intended to evoke the Statue of Liberty in New York Harbor.
Despite persistent reports of conflict between the two designers, Childs told a television interviewer they had "a spectacular time working together. ... Creative minds have different thoughts about how you do things. I wouldn't want to work with somebody who would just say yes."
Added Pataki: "This represents a melding of two very, very talented creative geniuses."
Negotiations had been contentious between the two architects. Libeskind, who created the Jewish Museum in Berlin but has little experience with major commercial projects, once compared the relationship with Childs, who designed the new Time Warner building in Manhattan, to a "forced marriage."
Several safety features were included in the design, such as separate staircases for firefighters and "blast-resistant glaze" on the lobby glass.
"We wanted it to be safe, not only for the eventual occupants ... but for the contractors and the workers who will be up there constructing the world's tallest building," Childs said at the news conference.