They would frame a massive memorial in a tree-filled park, plus a theatre and a transportation hub with uplifted wings - one of several symbols intended to defy the terrorists who destroyed the 16-acre site in under two hours.
Standing on the site now - a multi-level labyrinth of concrete and steel, from the entrance resembling the rooftops of an underground city - the sweeping design unveiled 6½ years ago still hasn't materialized.
And while the most symbolic pieces of the puzzle at ground zero are taking shape, it's become increasingly clear that the grand scheme will take decades to be fully completed, if it ever is at all.
Vickie Cooper had mixed feelings as she peered through a fence at the site's stark northeast corner, a spot reserved for a skyscraper now mired in arbitration over its financing.
Its history is "too sad to even really think about progress," said the 48-year-old Austin, Texas, insurance worker. But "I am a little surprised - I thought there'd be something built there."
When will there be? As the eighth anniversary of the 2001 terrorist attacks approaches, there's no firm due date for that office tower or two others supposed to help line the eastern side of the site; only one is under construction.
Developer Larry Silverstein has gone to an arbitrator to renegotiate his lease with the site's government owner after months of fruitless negotiations. An analysis done for the Port Authority of New York and New Jersey this spring projected there might be no market for Silverstein's third tower until 2030.
The fifth tower in the spiral is rarely discussed as viable. The spot reserved for it is still covered by a skyscraper contaminated with toxic debris from the attacks, its dismantling slowed after a 2007 blaze killed two firefighters. There's no finished design or money and little public pressure for the performing arts centre.
A poll last month found that more than half of New York City voters believe the rebuilding is going badly. More than 60 percent don't believe the highest-priority projects - the 1,776-foot Freedom Tower and the September 11 memorial - will be finished by announced deadlines.
The Quinnipiac University poll of 1,290 voters had a margin of sampling error of plus or minus 2.7 percentage points.
The doubts don't surprise Port Authority Executive Director Chris Ward.
"The only way you could cure that skepticism is to deliver on the things we are now delivering on," he said this week as roughly 1,000 workers labored on the site.
The Freedom Tower's frame is several stories above street level. Work has begun on one Silverstein tower and continues on underground elements of the US$3.2 ($NZ4.6) billion transit hub. The memorial pools' outline and plaza - some built from a pit 70 feet below ground to street level - have filled in a swath of the site.
"It's not a pit," Ward said. "Now, it's a sense of rebirth."
Daniel Libeskind's master design was chosen in early 2003 amid an atmosphere of unfettered possibility. Officials praised the plan's bold symbolism and its vision of a bustling business district enhanced by shops, restaurants and arts that repair the broken skyline and honour the nearly 2,800 people killed.
To Libeskind, it was and remains "a coherent and a complete vision."
"My hopes and my vision haven't changed," he said in an interview this week. "At the centre of the desire to do this is really to create an inspiring place ... an affirmation of American values."
Political wrangling, engineering complications and the recession pushed completion dates back and sent cost estimates up by billions of dollars since the first plans were released. The Port Authority pushed back its timeline last fall, saying the memorial, Freedom Tower and transit hub would open between 2011 and 2014.
Ward said the four office towers - three planned by Silverstein - would be built when the battered economy, which has emptied existing towers of commercial space across the city, allows it.
Assembly Speaker Sheldon Silver, whose district includes ground zero, said it's crucial to build all the planned office space, noting that terrorists deliberately struck at the nation's financial capital.
"We committed eight years ago that we were going to rebuild bigger and better than ever. If we're not going to do that, then we're sending a terrible message," he said.
Silverstein - who leased the towers six weeks before the attacks - has said the delays that he has blamed on the Port Authority have cost the project public confidence.
Putting off the office towers much longer would dishonour a commitment to respond to the attacks and "would really be a stain on New York's reputation and image," said Janno Lieber, who runs the project for Silverstein Properties.
Other local businesses fear being stuck around a construction site for years, said Kathryn Wylde, president of the Partnership for New York City, a business group.
"Can the site be made functional and attractive without completing it?" she said.
Some other key players involved in the planning now stress deliberation over bold strokes.
Former Gov. George Pataki stressed urgency at the site in dozens of speeches after unveiling a since-delayed timetable for the Freedom Tower in 2003.
In the beginning, "there was a tremendous sense of time urgency, and personally, I would like to see that continue today to every element of the site," said Pataki, who left office in 2006.
But how long ground zero takes to rebuild won't matter to future generations, he said.
"I'd rather have it right than yesterday, and this is being done right," Pataki said.
Libeskind - who envisioned it all - watches the construction from his studio window blocks away.
What ultimately gets built - whenever that happens - "will really be the plan that I drew, at its core."
He would not, he says, have done anything differently.
