New York (CNN) -- It has risen -- floor by floor, gleaming steel beam by steel beam -- from the scene of what was incomprehensible destruction more than a decade ago.
Now, as 1 World Trade Center in Lower Manhattan stretches closer toward being the tallest building in the United States, it already stands as an icon in its own right.
Punctuating the Manhattan horizon, the once-named "Freedom Tower" also was once fraught with controversy and costly redesigns. But it's soon expected to top off at 1,776 feet -- technically edging out the Willis Tower in Chicago by way of decorative spire affixed to its peak, and replacing the Twin Towers that fell to terrorist attacks on September 11, 2001.
"Everybody takes pride in this building," says Marc Becker, deputy general superintendent of the construction firm Tishman. "Everyone's an important piece of the puzzle, whether you're an iron worker, whether you're a painter, everyone has a job to do."
"We're all here to see this through to the end," adds Becker.
Crews at the site are gearing up for President Barack Obama's visit Thursday to the work-in-progress -- which now has reached 104 stories -- for an update on its upward growth.
The building is expected to open in about a year and a half.
"We're going to have our topping-out beam placed on the street" so that President Obama can sign it, says Mike Pinelli, general superintendent at 1 TWC.
"It's going be the first signature on the topping-out beam," he adds.
"It's typically signed by everybody on the project at some point and then we're going to erect it shortly thereafter to signify the topping out of Tower One."
On the 92nd floor, workers can often be seen hanging off beams as they twist steel rods into a lattice framework while blowtorches spray sparks against the upper floors.
Lacking external glass at such heights, the structure is edged by black netting to prevent loose objects from falling into the plaza more than a thousand feet below.
Ground was broken in April 2006, on a redesign by the architectural firm of Skidmore, Owings and Merrill, with construction starting later that year.
"The structure itself is a hybrid," says Mel Ruffini, Tishman's project executive. "The perimeter is steel, the core is concrete."
He calls it "the strongest concrete we've ever used in New York, maybe in the United States, for an office building."
"The walls are extremely thick, and all of the building supplies, elevators, all the risers, all telecommunications are within that concrete structure inside the building," he says.
From the 92nd floor, workers are able to watch planes approach the New York region's three major airports, a subtle reminder, they say, of the thousands who died on that September day.
"Tower One, when it's complete, will symbolize everything that was lost in 9/11," Pinelli says. "It also will symbolize our resiliency as a nation, all the hard work put in by everybody."