Gary He / Insider Images via EPA

The spire for the top of One World Trade Center is hoisted into place at the top of the building in New York City, on May 10, 2013. The spire has been put in place on One World Trade Center bringing the iconic structure to its full, symbolic height of 1776 feet.

Anthony Quintano / NBC News

WTC worker Tyler Brown taking in the view after the spire has been installed at the top of One World Trade Center.

A crane lifted the last of a 408-foot tall spire on top of One World Trade Center on Friday, a capstone to an emotional 12-year effort to replace the twin towers destroyed by terrorists.

The 18-piece silver spire will top out the tower at a symbolic 1,776 feet, a nod to the year America signed the Declaration of Independence. The new building is just north of the original towers, now the hallowed ground known as Ground Zero. Continue reading.

Mark Lennihan / AP

The final piece of spire is hoisted in place on top of One World Trade Center, on May 10, 2013 in New York. The addition of the spire, and its raising of the building's height to 1,776 feet, would make One World Trade Center the tallest structure in the U.S. and third-tallest in the world.

Lucas Jackson / Reuters

Iron workers look at names signed inside of the final piece of the spire on top of the One World Trade Center in New York on May 10, 2013. Workers cheered and whistled as they completed the spire on New York's One World Trade Center on Friday, raising the building to its full height of 1,776 feet and helping fill a void in the skyline left by the September 11, 2001 attacks.

Lucas Jackson / Reuters

An iron worker takes a photograph of a crane as it places the final piece of the spire on top of the One World Trade Center in New York on May 10, 2013.

Anthony Quintano / NBC News

The skyline of Manhattan from the top of One World Trade Center on May 10, 2013.

Gary He / Insider Images via EPA

The spire for the top of One World Trade Center is hoisted into place at the top of the building in New York, on May 10, 2013. The State of Liberty is seen bottom right.

Also on PhotoBlog:

• World Trade Center observatory gives visitors views of NYC from 1,250 feet
• 'Things from the heart': Workers at World Trade Center site scrawl graffiti of defiance, hope
• Freedom Tower spire arrives in New York City

Slideshow: The world's tallest skycrapers

Feng Li / Getty Images

Reaching for the sky, these buildings and towers compete for the world's attention.

Launch slideshow

Gary Hershorn / Reuters

The final section of the spire that will top off One World Trade Center is raised past iron workers to the top of the building in New York, on May 2. The spire will be permanently attached at a later date.

Construction crews on Thursday hoisted the final segment of spire that will top One World Trade Center and complete a piece of the New York City skyline missing since the 9/11 terror attacks.

A crane guided the final piece into a temporary structure that will house the section until final installation by iron workers at a later date.

Once installed, the spire — weighing more than 700 tons — will crown the Freedom Tower at 1,776 feet, making it the tallest building in the Western Hemisphere, according to the Port Authority of New York and New Jersey. The building currently tops out at 1,368 feet.

9/11 Memorial President Joe Daniels watched the spire piece rise Thursday morning from the memorial's office windows overlooking the World Trade Center site.

"It's a big milestone in the history of the rebirth of the site," Daniels told NBC News. "This renewal of spirit, to see spring here and this beautiful weather, the memorial fountains and the flag on the spire piece going up. It was one of those things that you won't forget."

By chance, the hoisting fell exactly two years after Navy SEALS shot and killed Osama Bin Laden, the mastermind behind the terror attacks that demolished the two World Trade Center towers and killed thousands of Americans.

"To have the One World Trade Center spire happen today — it feels poetic, and it feels like poetic justice," Daniels said.

The event came one day after a 250-pound piece of an airplane wing, believed to be part of a 9/11 jetliner, was removed out of an alley near the World Trade Center where it was found last week and taken into police custody.

When the building is completed, and once it is verified by the Council on Tall Buildings and Urban Habitat, One World Trade Center will be the third-highest building in the world, behind Dubai's Burj Khalifa (2,717 feet) and Mecca's Makkah Royal Clock Tower Hotel (1,972 feet).

Willis Tower (formerly called Sears Tower) and the Trump International Hotel & Tower, both in Chicago, are currently the two highest buildings in the U.S.

The spire — complete with galvanized steel broadcast rings — will serve as part of the One WTC's transmission facilities for the region's media outlets. Perched at its tip is the spire's stainless steel beacon.

A large group of spectators gathered to watch the needle's ascent on Thursday.

Tourist Moulen Katherine called the spectacle "impressive" and "emotional."

Rick and Cindy Baldwin of Charlotte, N.C., had just arrived in New York City and called the sight "inspiring" and felt "excited to be part of New York City."

"I'm more interested in watching the people, they are as inspiring as the spire — the camaraderie they feel as they watch it  rise... we get to be part of history," Cindy Baldwin said.

Pockets of workers and tourists watched as two building crew members affixed an American flag to the spire.

Just outside the scrum, two building crew members, clad in white hard hats and neon yellow safety vests, called to each other from the sidewalk: "How you doing — all right?"

"Yeah, just trying to get a good picture," said the other as he raised his phone for a photo.

The spire's pieces were scheduled to be raised Monday but were delayed by wind.

Mark Lennihan / AP

Workers attach a harness to the final piece of spire before it is hoisted to the roof of One World Trade Center, on May 2.

Justin Lane / EPA

People watch as the spire is hoisted to the top of One World Trade Center in New York, on May 2. Once the spire is put in place One World Trade Center will be the tallest building in the western hemisphere.

Lucas Jackson / Reuters

An ironworker uses a line to steady the final piece of a spire, affixed with a U.S. flag, before it is lifted to the top of One World Trade Center in New York, on May 2.

Justin Lane / EPA

Workers watch as the spire for the top of One World Trade Center is hoisted to the top of the building in New York, on May 2.

Spencer Platt / Getty Images

Manhattan is seen from One World Observatory on the 100th floor of One World Trade Center at the Ground Zero site on April 2, 2013, in New York City. One World Observatory, which is situated more than 1,250 feet over lower Manhattan, will open to the public in 2015 and will include a pre-show theater, multiple spaces that allow for panoramas of the New York City region and numerous dining options. When completed, One World Trade Center will be the tallest building in the Western Hemisphere at 1,776 feet.

Lucas Jackson / Reuters

The Empire State Building is visible behind in the distance as a worker cleans the windows of the 100th floor observation deck in One World Trade Center before a press conference in New York, on April 2.

Spencer Platt / Getty Images

Pedestrians cross the street in lower Manhattan as seen from One World Observatory on the 100th floor of One World Trade Center at the Ground Zero site on April 2, in New York City.

The observation deck at One World Trade Center will not open until 2015 but the tower's developers are offering a glimpse of what they call the guest experience.

The observation deck will occupy the tower's 100th through 102nd floors. Elevators will whisk visitors to the top in just one minute but the experience of visiting the attraction will take an hour. Continue reading.

--The Associated Press

Lucas Jackson / Reuters

Members of the media are reflected in the windows of the 100th floor observation deck in the One World Trade Center in New York, on April 2.

Lucas Jackson / Reuters

The rising sun hits the side of One World Trade Center as it stands among other buildings in New York, on April 2.

Previously on PhotoBlog:

• Last beam lifted into place atop 4 World Trade Center
• One World Trade Center now taller than the Empire State Building, making it Manhattan's tallest
• One World Trade Center rises, providing breathtaking view of Manhattan

Keith Bedford / Reuters

Stephen Knapp, center left, is comforted by Charles Maikish, former World Trade Center director, as mourners and family members of victims participate in a 20th anniversary memorial for victims of the 1993 bombing of the World Trade Center in New York on Feb. 26.

Justin Lane / EPA

Flowers are seen next to the North Tower Reflecting Pool.

A moment of silence was observed at 12:18 p.m., the time when a truck bomb was detonated below the north tower on Feb. 26, 1993. The victims' names were read by family members before bagpipers played "Amazing Grace."

More than 1,000 people were injured in the 1993 blast in an underground garage below one of the towers. It was the first dramatic demonstration that "terrorism is theater and New York is the biggest stage," Police Commissioner Raymond Kelly said last week.

Verena Dobnik, The Associated Press

Read the full story.

Mark Lennihan / AP, file

Ironworkers James Brady, left, and Billy Geoghan release the cables from a steel beam after connecting it on the 104th floor of One World Trade Center in New York on Aug. 2, 2012. The beam was signed by President Barack Obama with the words: "We remember," ''We rebuild" and "We come back stronger!" during a ceremony at the construction site June 14. Also adorned with the autographs of workers and police officers at the site, the beam will be sealed into the structure of the tower, which is scheduled for completion in 2014.

Mark Lennihan / AP

Graffiti left by visitors to One World Trade Center is seen on a steel column on the 104th floor on Jan. 15, 2013.

The Associated Press reports — On most construction projects, workers are discouraged from signing or otherwise scrawling on the iron and concrete. At the skyscraper rising at ground zero, though, they're being invited to leave messages for the ages.

"Freedom Forever. WTC 9/11" is scrawled on a beam near the top of the gleaming, 104-story One World Trade Center. "Change is from within" is on a beam on the roof. Another reads: "God Bless the workers & inhabitants of this bldg."

The words on beams, walls and stairwells of the skyscraper that replaces the twin towers lost on Sept. 11, 2001, form the graffiti of defiance and rebirth, what ironworker supervisor Kevin Murphy calls "things from the heart." Read the full story.

Related:

One World Trade Center rises, providing breathtaking views of Manhattan

View a panoramic image of the National Sept. 11 Memorial

Ground Zero ten years later

Mark Lennihan / AP

The name Antony is seen on a steel column on the 102nd floor of One World Trade Center on Jan. 15, 2013. Workers finishing New York's tallest building are leaving their personal marks on the concrete and steel in the form of graffiti.

Mark Lennihan / AP

A message left by Michael Chertoff, the former director of Homeland Security, on a steel column on the 104th floor of One World Trade Center, seen on Jan. 15, 2013.

Chris Pedota / Pool via Getty Images

Parts of the spire for the Freedom Tower make their way on a barge to lower Manhattan on Dec. 11 in New York City.

By NBC News and news services

Chris Pedota / Pool via Getty Images

The barge is carrying nine pieces of steel that will eventually top off One World Trade Center at a symbolic 1,776 feet, becoming the tallest building in the Western Hemisphere.

The pieces that make up the giant spire that will sit atop the World Trade Center's tallest building arrived in New York City on Tuesday.

A barge carried nine pieces of the 408-foot steel spire across New York Harbor from New Jersey's Port Newark.

Meanwhile, workers on the 104-story skyscraper were busy pouring concrete that will hold the spire.

One World Trade Center rises, providing breathtaking views of Manhattan

The trade center's director of construction, Steven Plate, said the spire marks a post-9/11 milestone that signifies New York City is "better than ever."

The heaviest piece weighs nearly 70 tons.

SPI, dbox via Getty Images

An artist's rendering shows the lower Manhattan skyline as proposed after the construction of the future Freedom Tower, left, and other buildings.

The spire is expected to rise into the Manhattan sky by spring.

Plate says the 1,776-foot high-rise — symbolizing America's freedom — will be the tallest building in the Western Hemisphere.

View a panoramic image of the National Sept. 11 Memorial

The high-rise is one of five new skyscrapers planned for the new World Trade Center. The project will also include a 9/11 memorial and museum, a transportation hub, 550,000 square feet of retail space and a performing arts center.

The twin towers of the old World Trade Center collapsed after hijackers flew airplanes into them on Sept. 11, 2001.

The Associated Press contributed to this story.

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Gary Hershorn / Reuters

The Tribute in Light is illuminated on the skyline of New York during events marking the 11th anniversary of the 9/11 attacks on the World Trade Center as people watch from Liberty State Park in Jersey City, New Jersey, September 11, 2012.  Continue reading the full story.

See more PhotoBlog posts on 9/11

Slideshow: Marking the 11th anniversary of 9/11

Ceremonies at World Trade Center, the Pentagon, and Shanksville, Pa. mark 11 years since the attacks.

Launch slideshow

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Chris Pedota / Pool via AFP - Getty Images

A small US flag stands at September 11 memorial during observances on the eleventh anniversary of the attacks on the World Trade Center, on September 11, 2012 in New York.

Jeff Swensen / Getty Images

A Marine Honor Guard lays a wreath in front of the Wall of Names at the Flight 93 National Memorial during observances commemorating the eleventh anniversary of the 9/11 attacks, on Sept. 11, 2012 in Shanksville, Penn.

Slideshow: Marking the 11th anniversary of 9/11

Ceremonies at World Trade Center, the Pentagon, and Shanksville, Pa. mark 11 years since the attacks.

Launch slideshow

From NBC News and wire services - Thousands gather Tuesday in New York, suburban Washington and rural Pennsylvania to mark the 11th anniversary of the Sept. 11 attacks, but at the somber day's biggest venue, Ground Zero in lower Manhattan, this year's observance will be missing a key feature from years past: politicians' voices.

In a reminder of the global consequences of the attacks, commemorations will also be held abroad. At the Kaia airport in the Afghan capital Kabul, soldiers with the NATO-led International Security Assistance Force prayed during a memorial ceremony for the Sept. 11 victims. Continue reading this post here.

• View a 360 degree panoramic image of the National September 11 Memorial at dusk
• Testing the Tribute of Light in New York
• One World Trade Center rises, providing breathtaking view of Manhattan
• View a panoramic image of the National September 11 Memorial before it opened in 2011
• 9/11 memorial to cost $60 million a year to operate
• Anniversary of 9/11 marked under cloud of health problems, funding fights

Craig Ruttle/ Pool via Getty Images

Joe Torres of Sayreville, New Jersey, a fire captain from Elizabeth, New Jersey, kneels as he touches the name of his sister-in-law Krystine Bordenabe during memorial ceremonies for the eleventh anniversary of the terrorist attacks on lower Manhattan at the World Trade Center site September 11, 2012 in New York City. New York City and the nation are commemorating the eleventh anniversary of the September 11, 2001 attacks which resulted in the deaths of nearly 3,000 people after two hijacked planes crashed into the World Trade Center, one into the Pentagon in Arlington, Virginia and one crash landed in Shanksville, Pennsylvania.

Justin Lane-Pool / Pool via Getty Images

Christine Gonda places a picture of firefighter George Kane in the engraving of his name at the South Pool during memorial ceremonies for the eleventh anniversary of the terrorist attacks on lower Manhattan at the World Trade Center site September 11, 2012 in New York City.

Gary Hershorn / Reuters

Jeremy Hamilton places a U.S. flag next to a memorial bearing two pieces of steel from the World Trade Center in Weehawken, New Jersey, across from the skyline of New York, September 11, 2012. Thousands gathered in New York, Washington and Pennsylvania to mark the 11th anniversary of the September 11 attacks.

Shawn Thew / EPA

A couple stand near a memorial bench at the Pentagon 9/11 Memorial prior to the 11th Anniversary ceremony of the September 11, 2001 attacks at the Pentagon in Arlington, Virginia.

Mark Lennihan / AP

The tower known as 1 World Trade Center, left, the National September 11 Memorial, bottom left, and 4 World Trade Center, right, are bathed in light, Tuesday, Sept. 11, 2012 in New York. Tuesday is the eleventh anniversary of the terrorist attacks of Sept. 11, 2001.

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A 360 degree panoramic image of the National September 11 Memorial. ( John Makely and Jonathan Sanger / NBC News )

John Makely / NBC News

The names displayed at the memorial are grouped by attack at The National September 11 Memorial in New York.

By John Makely / NBC News - As night falls, the National September 11 Memorial takes on a whole different feeling. Crowds become sparse, construction ceases and the traffic of lower Manhattan seems to fade away. You are left with the sounds of cascading water and the rustling of trees.  There is no better place to reflect on what happened on September 11, 2001, and the lives that were lost.

John Makely / NBC News

A couple pauses for a moment near the the south reflecting pool at the National September 11 Memorial in New York.

John Makely / NBC News

In the evening the names of those who died in the attacks are illuminated.

Jonathan Sanger / NBC News

Water cascades into the south reflecting pool.

John Makely / NBC News

The tridents, two relics of the destroyed towers, are seen through the glass enclosure that will be the entrance to the National September 11 Museum once it opens.

Related Links:

• Testing the Tribute of Light in New York
• One World Trade Center rises, providing breathtaking view of Manhattan
• View a panoramic image of the National Sept. 11 Memorial before it opened in 2011
• 9/11 memorial to cost $60 million a year to operate
• Anniversary of 9/11 marked under cloud of health problems, funding fights

Follow this link for information about tickets to the Memorial.

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Keith Bedford / Reuters

Construction workers and guests watch as the final steel beam to be installed on 4 World Trade Center is raised during a ceremony in New York, June 25.

Spencer Platt / Getty Images

Construction workers sign the last steel beam before it is hoisted 977 feet to the top of Four World Trade Center on June 25, in New York City.

Andrew Gombert / EPA

The last steel beam is lifted to the top of 4 World Trade Center, June 25.

The final steel beam, signed by a group of construction workers was lifted by crane 977 feet in the air and placed atop 4 World Trade Center, which will be the first tower completed on the 16-acre World Trade Center site when it opens in the fall of 2013.  Full story.

Mark Lennihan / AP

In a photo made Saturday, June 23, 2012, construction cranes perch on top of One World Trade Center, left, and Four World Trade Center in New York.

Kevin Lamarque / Reuters

U.S. President Barack Obama and first lady Michelle Obama look down at the 9/11 Memorial while touring the One World Trade Center building which is under construction in New York on June 14.

Jewel Samad / AFP - Getty Images

Barack Obama signs a steel beam as First Lady Michelle Obama, New York governor Andrew Cuomo, New Jersey governor Chris Christie and New York Mayor Michael Bloomberg look on at the One World Trade Center site in New York on June 14.

Justin Lane / EPA

Iron workers take pictures of the signatures of President Barack Obama and First Lady Michele Obama after a ceremony where they signed a steel beam that will be used to top off the One World Trade Center in New York.

Justin Lane / EPA

A view of President Barack Obama's signature on a steel beam that will be used to top of One World Trade Center.

President Barack Obama and First Lady Michelle Obama visited Ground Zero in New York City to review the construction of the iconic 104-story skyscraper that replaces the World Trade center towers destroyed on Sept. 11, 2001.

The Obamas toured the 22nd floor of One World Trade Center and also signed their names on a steel beam that will be added to the tower's construction with the message, "We remember, we rebuild, we come back stronger!"

During his trip to New York, the president will also be attending campaign fundraisers at the home of Sarah Jessica Parker and Matthew Broderick, and at the Plaza Hotel.

Spencer Platt / Getty Images

People stand on posts while waiting for the Presidential motorcade to pass on June 14 in New York City. President Obama came to New York Thursday for a briefing on the progress of the iconic 104-story tower that replaces the World Trade center towers destroyed on 9/11.

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