The countdown has begun.
With just six months until the 10th anniversary of the Sept. 11 attacks, thousands of construction workers are toiling amid metal and concrete in the middle of the World Trade Center site.
Their goal is to finish "Reflecting Absence," the memorial that honors the victims of Sept. 11 with two reflecting pools evoking the footprints of the fallen towers. It is set to open the day the nation marks the somber milestone.
9/11 Memorial President Joe Daniels describes the memorial as it is supposed to look that day, with 30-foot waterfalls flowing into the pools, the 400 trees on the street-level plaza and sunlight falling on the names of the nearly 3,000 victims.
"All those things together is going to being a lot of closure, a lot of peace, a place to just stop and reflect," Daniels said.
Online reservations for the memorial are expected to be available starting this summer.
After years of delays and real estate squabbles, government officials declared the memorial their top priority. There are now office towers rising from the 16-acre site, but none will be complete in time for the anniversary.
But the memorial will be finished, said Chris Ward, executive director of the Port Authority of New York and New Jersey, which controls the site.
"The world will have a place to gather and remember on the 10-year anniversary," Ward said.
Other milestones are scheduled to follow.
One World Trade Center, which was once called the Freedom Tower, is now 58 stories high.
Ward predicted it will reach its finished height of 104 stories by September. But completing the interior of the tower, including desks and offices for Conde Nast, which has leased up to 35 stories, will take at least another year.
The PATH station, which is designed to merge with the MTA's Fulton transit hub, is scheduled for completion in 2014, including a soaring archway from architect Santiago Calatrava.
And developer Larry Silverstein is expected to open what is known as Tower 4, at the southeast corner of the site, next year. Progress had been stalled for years because of a financial dispute between Silverstein and the PA.
Some say the delays came at great emotional cost, and that the memorial to the victims should have been built long ago to help soothe a stunned city.
"It took too long," said Marlene Tapper, who works a few blocks from the site and prays at Trinity Church, which sits near ground zero at Broadway and Wall Street. "I mean, we put up buildings in what, six months? Skyscrapers. So, I think it will give people something to actually feel closure. Like when someone passes and you go to the cemetery."
The memorial plaza is eight acres -- bigger than Bryant Park -- and will eventually feature 400 Swamp White oak trees.
The below-ground museum is expected to be completed in 2012. A partially-built pavilion now houses two steel tridents from the original north tower, which are visible at street level.
The glass atrium will be lit at night, said Daniels, the memorial president, to "serve as a beacon to everybody, letting them know that this is where the event took place."