Construction of One World Trade Center

One World Trade Center is considered the first major building whose construction is based upon a three-dimensional Building Information Model.{{Cite news|url=https://www.wsj.com/articles/SB108915978482156861|title=New Dimensions in Design|last=Frangos|first=Alex|date=2004-07-07|work=Wall Street Journal|access-date=2018-03-23|language=en-US|issn=0099-9660}} The symbolic cornerstone of One World Trade Center was laid down in a ceremony on July 4, 2004,{{cite press release|url=http://www.state.ny.us/governor/press/04/july4_04.htm |title=Governor Pataki, Governor McGreevey, Mayor Bloomberg Lay Cornerstone for Freedom Tower |date=July 4, 2004 |publisher=Office of the Governor of New York State |url-status=dead |archive-url=https://web.archive.org/web/20061231232307/http://www.state.ny.us/governor/press/04/july4_04.htm |archive-date=December 31, 2006 }} but further construction of the tower was stalled until 2006. The cornerstone was temporarily removed from the site on June 23, 2006.{{cite news|url=http://www.cbsnews.com/stories/2006/06/25/ap/national/mainD8IF1PB80.shtml|archive-url=https://web.archive.org/web/20070108140050/http://www.cbsnews.com/stories/2006/06/25/ap/national/mainD8IF1PB80.shtml|archive-date=January 8, 2007|title=Cornerstone of Freedom Tower removed|date=June 25, 2006|work=CBS News}} The project was delayed due to disputes over money, security and design but the last major issues were resolved on April 26, 2006 with a deal between developer Larry Silverstein and the Port Authority of New York and New Jersey. During the summer of 2006, explosives were detonated at the World Trade Center construction site, testing the use of charges to clear bedrock for the building's foundation. Controlled explosions continued for approximately two months thereafter.

Image:Freedom Tower August 7th 2007.jpg

On November 18, 2006, {{convert|400|cuyd|m3|abbr=off|sp=us}} of concrete were poured onto the foundation of the One World Trade Center, carried by as many as 40 trucks. On December 17, 2006, a ceremony was held in Battery Park City, with the public invited to sign a {{convert|30|ft|m|adj=on}} steel beam.{{cite news |url=https://www.nytimes.com/2006/12/18/nyregion/18zero.html?ref=nyregion|title=Messages of Love and Hope on a Freedom Tower Beam |date=December 18, 2006 |author=Chan, Sewell |work=The New York Times}} This beam, the first to be installed, was welded onto the building's base on December 19, 2006.{{cite news|url=http://wcbstv.com/topstories/local_story_353063928.html|archive-url=https://web.archive.org/web/20061220065543/http://wcbstv.com/topstories/local_story_353063928.html |archive-date=December 20, 2006|title=First Freedom Tower Beam Rises At Ground Zero |publisher=WCBS-TVV |date=December 19, 2006}}

On January 9, 2007, a second set of beams was welded to the top of the first set. February 2007 estimates put the cost for construction of 1 WTC at $3 billion, or $1,150 per square foot ($12,380 per square meter). Approximately $1 billion of insurance money recouped by Silverstein in connection with the September 11 attacks is being used for construction of the new One World Trade Center.{{cite news|url=https://www.nytimes.com/2007/02/16/opinion/16nordenson.html |title=Freedom From Fear |work=The New York Times |date=February 16, 2007|author=Nordenson, Guy}} The State of New York is expected to provide $250 million toward construction costs, and the Port Authority agreed to finance another $1 billion through bonds.{{cite news|url=https://select.nytimes.com/gst/abstract.html?res=F00916F7345B0C708DDDAB0894DF404482 |title=Spitzer, in Reversal, Is Expected to Approve Freedom Tower, Officials Say |work=The New York Times |date=February 13, 2007 |author=Bagli, Charles V.}} In 2007, Tishman Construction Corporation of New York completed a row of steel columns at the perimeter of the construction site. Two tower crane bases were erected, each base containing a functioning luffing-jib tower crane. By the end of 2007, the tower's footings and foundations were nearly complete.{{cite press release |url=http://www.panynj.gov/AboutthePortAuthority/PressCenter/PressReleases/PressRelease/index.php?id=1019 |title=Statement by Port Authority Regarding Preparation of Towers 3 and 4 Bathtub at WTC Site to Allow Silverstein Properties to Begin Construction in January |date=December 31, 2007 |publisher=Port Authority of New York & New Jersey |url-status=dead |archive-url=https://web.archive.org/web/20090916071342/http://www.panynj.gov/AboutthePortAuthority/PressCenter/PressReleases/PressRelease/index.php?id=1019 |archive-date=2009-09-16 }}

In January 2008, two construction cranes were moved into the construction site. The tower's concrete core began rising in the first months of 2008. By February 22, 2008, 9,400 of the nearly {{convert|50000|ST|t}} of steel necessary had been ordered.{{cite news | url=http://www.highbeam.com/doc/1A1-D8UVGEL01.html | archive-url=https://web.archive.org/web/20150924041419/http://www.highbeam.com/doc/1A1-D8UVGEL01.html | url-status=dead | archive-date=September 24, 2015 | title=Long Journey of Freedom Tower Steel | agency=Associated Press | author=Westfeldt, Amy | date=February 22, 2008|access-date=2015-08-06}} By March 13, 2008, the steel for the tower had reached {{convert|70|ft|m}} high, {{convert|10|ft|m|0}} below street level.{{cite news |url=http://www.globest.com/news/1113_1113/newyork/169019-1.html |title=Silverstein: WTC Still on Track for 2012 Finish |publisher=GlobeSt.com |author=Ritter, Ian |date=March 13, 2008 |access-date=2011-08-28 |archive-url=https://web.archive.org/web/20110927182312/http://www.globest.com/news/1113_1113/newyork/169019-1.html |archive-date=2011-09-27 |url-status=dead }}{{cite web|url=http://www.wtc.com/news/rising-from-the-pit|title=Rising from the Pit|publisher=WTC.com|date=March 17, 2008}} From late March through early April, a {{convert|40|ft|m|0|adj=on}} tall mockup of a section of the tower's wall with twenty-four windows was tested by Construction Consulting Laboratory West in Ontario, California. The purpose of the testing was to ensure that the all-glass exterior of the tower will be able to withstand earthquakes and extreme weather conditions.{{cite news| first=Tom | last=Topousis | url=http://www.nypost.com/seven/04012008/news/regionalnews/freedom_rattled_104483.htm | title='FREEDOM' RATTLED| work=New York Post | date=April 1, 2008}} Testing also took place on another full-scale mockup south of Albuquerque, New Mexico. Both mockups passed the tests.{{cite news | first=David W. | last=Dunlap |url=https://www.nytimes.com/2008/04/09/nyregion/09freedom.html?ex=1365480000&en=17d1a74af4e5ca17&ei=5124&partner=permalink&exprod=permalink |title=Replicas of New Tower Endure Nature's Fury and a Test Blast | work=New York Times | date=April 9, 2008}} In mid-April, a batch of concrete had to be replaced after it failed a stress test.{{cite news |url=http://www.ny1.com/ny1/content/index.jsp?stid=8&aid=80570 |title=Weak Concrete Foundation Removed From Freedom Tower |work=NY1 |date=April 16, 2008 |access-date=April 19, 2008 }}{{dead link|date=November 2017 |bot=InternetArchiveBot |fix-attempted=yes }}

On May 17, 2008, the tower's steel reached street level when new sections were bolted to two of the twenty-four jumbo steel columns marking the building's footprint. The new column sections brought the height of the structure up to {{convert|15|ft|m}} above street level.{{cite news | first=David W. | last=Dunlap |url=http://cityroom.blogs.nytimes.com/2008/05/19/not-yet-on-the-skyline-but-above-street-level/ | title=Not Yet on the Skyline, but Above Street Level |work=New York Times | date=May 19, 2008}} In June, the chamfered steel skeleton of the tower's concrete base had begun to take shape.{{cite news | first=David W. | last=Dunlap |url=http://cityroom.blogs.nytimes.com/2008/06/19/chamfer-anyone-cutting-corners-on-a-large-scale/ | title=Chamfer, Anyone? Cutting Corners on a Large Scale |work=New York Times | date=June 19, 2008 | access-date=July 13, 2008}} By the end of the month, the concrete had been poured for the floor of the tower's basement level B3.{{cite news | first=David W. | last=Dunlap |url=http://cityroom.blogs.nytimes.com/2008/07/03/the-choreography-quickly-of-concrete/ | title=The Choreography (Quickly!) of Concrete|work=New York Times | date=July 3, 2008 | access-date=July 13, 2008}} In his June 30, 2008 World Trade Center Rebuilding Assessment to the then New York Governor David Paterson, Port Authority executive director Christopher O. Ward noted that roughly 90 percent of the construction contracts had been bid.{{cite report |title=World Trade Center Site Update |last=Ward |first=Chris|year=2008 |publisher=Port Authority of New York and New Jersey |pages=13|url=http://www.panynj.gov/AboutthePortAuthority/pdf/WTC_Assessment_Book_FFF.pdf |access-date=June 30, 2008 }}

Image:World Trade Center Site 200907.jpg

By August, 1 WTC had reached {{convert|25|ft|m}} above street level.{{cite news |first=Michael |last=Frazier |url=http://www.newsday.com/news/local/newyork/ny-nywtc0818,0,4404790.story |title=Construction progress slow at World Trade Center site |work=Newsday |publisher=Newsday Inc. |location=Melville, New York |date=August 17, 2008 |url-status=dead |archive-url=https://web.archive.org/web/20080901154543/http://www.newsday.com/news/local/newyork/ny-nywtc0818%2C0%2C4404790.story |archive-date=September 1, 2008 }} During its September 16 meeting, the Port Authority board approved contracts for security and building management systems,{{cite press release | url=http://www.panynj.gov/AboutthePortAuthority/PressCenter/PressReleases/PressRelease/index.php?id=1121 | title=Port Authority Board Takes Action on Several items | date=September 16, 2008 | publisher=Port Authority of New York & New Jersey | access-date=August 28, 2011 | archive-date=November 20, 2018 | archive-url=https://web.archive.org/web/20181120111928/http://www.panynj.gov/AboutthePortAuthority/PressCenter/PressReleases/PressRelease/index.php?id=1121 | url-status=dead }} and 95% of the contracts needed to complete the tower had been signed.{{cite news | url=http://www.wnyc.org/news/articles/109346 | title=Port Authority Approves Freedom Tower Contracts | work=WNYC | first = Bob | last = Hennelly | date=September 16, 2008 | access-date =September 18, 2008}} The $20 million security contract includes sophisticated video analysis in which computers would alert security personnel to abnormal situations automatically.{{cite news | first=David W. | last=Dunlap|url=http://cityroom.blogs.nytimes.com/2008/09/24/unblinking-eyes-for-20-million-at-freedom-tower/ | title=Unblinking Eyes, for $20 million, at Freedom Tower |work=New York Times | date=September 24, 2008 | access-date=September 24, 2008}} On October 10, Collavino Construction poured an additional {{convert|520|cuyd|m3}} of concrete for the tower's concrete core, raising it to just above street level.{{cite news | first=David W. | last=Dunlap |url=http://cityroom.blogs.nytimes.com/2008/10/20/phantom-freedom-tower-now-visible-to-all/ | title=Phantom Freedom Tower Visible to All|work=New York Times | date=October 20, 2008 | access-date=October 21, 2008}}

By February 11, 2009, the tower was {{convert|105|ft|m}} above street level.{{cite news|url=http://www.panynj.gov/wtcprogress/image_gallery.html |title=Image Gallery |publisher=Port Authority of New York and New Jersey |date=February 11, 2009 |access-date=February 21, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090215053207/http://www.panynj.gov/wtcprogress/image_gallery.html |archive-date=February 15, 2009 }} On July 2, 2009, over {{convert|1200|cuyd|m3}} of concrete were poured to form parts of the street-level plaza. On August 13, the builders of 1 WTC set a {{convert|70|ST|kg|abbr=off}} piece of steel into place—the largest column installed yet at the building. Each steel column, made at a factory in Luxembourg, was about {{convert|60|ft|m}} long. The columns at the bottom of the tower's foundation were about {{convert|35|ft|m}} long.{{cite web|url=https://www.nbcnews.com/id/wbna32391977 |title=Huge column is largest installed at WTC tower – Life|work=NBC News |date=August 12, 2009 |access-date=March 13, 2010}}

By November 1, 2009, the twenty-four perimeter columns of 1 WTC were all erected, and construction of the second floor (the first floor above ground level) was nearly complete. In addition, The Port Authority of New York and New Jersey reported in their 2009 Q3 Annual Report that steel erection should commence by January 2010, and that the typical floor construction could begin.{{cite web |url=http://www.panynj.gov/wtcprogress/pdf/3Q2009_Report.pdf |title=World Trade Center Quarterly Report 3rd Quarter 2009 – Panynj.gov |access-date=2011-11-17 |archive-date=2011-09-29 |archive-url=https://web.archive.org/web/20110929044910/http://www.panynj.gov/wtcprogress/pdf/3Q2009_Report.pdf |url-status=dead }}

Steel and concrete installation continued in 2010, where two cranes were on site. The fifth floor was finished on January 16. In February, construction began on the sixth floor, the last floor of 1 WTC's base, and the Port Authority announced that the tower's steel superstructure had reached {{convert|200|ft|m}} above street level.[http://www.lowermanhattan.info/construction/project_updates/freedom_tower_26204.aspx1 World Trade Center (Freedom Tower)] {{webarchive|url=https://web.archive.org/web/20110928014507/http://www.lowermanhattan.info/construction/project_updates/freedom_tower_26204.aspx1 |date=2011-09-28 }} Lower Manhattan.info. Retrieved 2010-2-4. By the end of March 2010, steel beams began to be erected for the second office floor. In April, the 45-degree octagon was installed, the building's steel frame had reached 26 floors, and concrete was completed on the base structure in the latter part of the month.[http://www.silive.com/news/index.ssf/2010/02/1_world_trade_center_reaches_2.html 1 World Trade Center reaches 20th-floor level]SITimes. Retrieved March 20, 2010.

In May 2010, the Port Authority stated that they were building close to one floor per week, and was projected that One World Trade Center would reach 55 stories by the end of 2010.[http://www.nj.com/opinion/times/oped/index.ssf?/base/news-1/1273124715235280.xml&coll=5 World Trade Center project has begun to take shape] {{Webarchive|url=https://archive.today/20120629050206/http://www.nj.com/opinion/times/oped/index.ssf?/base/news-1/1273124715235280.xml&coll=5 |date=2012-06-29 }} New Jersey On-line. Retrieved May 12, 2010. The cocoon system was also installed, marking the first time a cocoon safety system has been installed on a steel superstructure in the city.[http://www.nj.com/news/index.ssf/2010/05/port_authority_installs_cocoon.html Port Authority installs cocoon safety system around World Trade Center steel structure] NJ.com, May 2010

On July 13, 2010, workers found remains of an 18th-century sailing ship at the World Trade Center site while excavating for the underground Vehicle Security Center for One World Trade Center.[http://cityroom.blogs.nytimes.com/2010/07/14/18th-century-ship-found-at-trade-center-site/ 18th-Century Ship Found at Trade Center Site]. The New York Times. Retrieved July 15, 2010 The remains of a {{convert|32|ft|m|adj=on}} section of the ship's hull and a {{convert|100|lb|kg|adj=on}} anchor were found. The hull had been truncated and the beams sawed.[https://web.archive.org/web/20100716212619/http://www.foxnews.com/scitech/2010/07/14/ship-buried-th-century-unearthed-wtc-site/ Ship Buried in 18th Century Unearthed at WTC Site]Fox News Retrieved July 15, 2010 The ship was likely used as landfill material during the early 19th century to help expand Manhattan. Timbers from the ship were removed and sent to a laboratory to try to date the vessel.[http://www.latimes.com/news/la-naw-wtc-ship-20100715,0,3344391.story Buried ship found at World Trade Center site]. Los Angeles Times Retrieved July 15, 2010 An additional section of the ship was found on the site in August 2011, giving historians more information about the vessel, which was active around the 1770s.{{Cite web|last=Dunlap|first=David W.|date=2011-08-05|title=The World Trade Center Ship, From Stern to Stem|url=https://cityroom.blogs.nytimes.com/2011/08/05/the-world-trade-center-ship-from-stern-to-stem/|access-date=2020-09-22|website=City Room|language=en-US}}{{Cite web|date=2011-08-31|title=Pictures: 18th-Century Ship Found Under 9/11 Site|url=https://www.nationalgeographic.com/news/2011/8/11-world-trade-center-ship-ground-zero-new-york-nation-science/|archive-url=https://web.archive.org/web/20200813033405/https://www.nationalgeographic.com/news/2011/8/11-world-trade-center-ship-ground-zero-new-york-nation-science/|url-status=dead|archive-date=August 13, 2020|access-date=2020-09-22|website=National Geographic News|language=en}}

By October 2010, the tower's steel superstructure reached 44 stories.{{cite web |url=http://www.wtc.com/news/port-authority-board-approves-agreement-that-will-fully-restore-wtc-site |title=Port Authority Board Approves Agreement that Will Fully Restore WTC Site |publisher=Wtc.com |date=2011-09-19 |access-date=2011-11-17 |url-status=dead |archive-url=https://web.archive.org/web/20111001042340/http://www.wtc.com/news/port-authority-board-approves-agreement-that-will-fully-restore-wtc-site |archive-date=2011-10-01 }}[http://www.democratandchronicle.com/article/20101028/NEWS01/101028004 World Trade Center tower reaches 44 stories high and curtain wall installation this month] Rochester Democrat and Chronicle Retrieved October 29, 2010 In November, stainless steel and glass facade panels were being prepared for later installation, with the panels scheduled to be assembled between the 20th and 24th floors.[http://www.dnainfo.com/20101008/downtown/one-world-trade-center-prepares-shine One World Trade Center Prepared to Shine] {{webarchive|url=https://web.archive.org/web/20110723130708/http://www.dnainfo.com/20101008/downtown/one-world-trade-center-prepares-shine |date=2011-07-23 }} Digital Network Associates Info Retrieved November 17, 2010 On November 13, the first glass facade panels were installed on the 20th floor. Steven Coleman, spokesman for the Port Authority, stated, "Once they get rolling, they'll be able to install glass panels at a rate of one floor per week."{{cite web|url=http://www.wtc.com/news/world-trade-center-tower-begins-to-show-its-shimmering-face |title=World Trade Center Tower Begins to Show Its Shimmering Face || News || World Trade Center || |publisher=Wtc.com |date=2011-09-19 |access-date=2011-11-17}} By November 17, the tower's steel had reached 48 stories.{{cite web |url=http://www.tribecatrib.com/news/2010/november/799_world-trade-center-tower-begins-to-show-its-shimmering-face.html |title=World Trade Center Tower Begins to Show Its Shimmering Face |publisher=The Tribeca Trib |access-date=2011-11-17 |url-status=dead |archive-url=https://web.archive.org/web/20110928044854/http://www.tribecatrib.com/news/2010/november/799_world-trade-center-tower-begins-to-show-its-shimmering-face.html |archive-date=2011-09-28 }}

The Port Authority announced on December 16, 2010 that 1 WTC had reached the 52nd floor, and had risen to over {{convert|600|ft|m}}, marking the halfway point for the construction of the building's steel frame.[https://www.wsj.com/articles/AP963a03879d90473a8e230286ac9086e3 "1 WTC, aka Freedom Tower, reaches halfway mark"], The Wall Street Journal/Associated Press, December 16, 2010[http://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=10694936 "Freedom Tower half complete"] New Zealand Herald Retrieved December 17, 2010

By February 2011, the tower had reached 56 floors, {{convert|667|ft|m}} above grade, while the glass panels reached the 27th floor.[http://www.panynj.gov/wtcprogress/pdf/feb2011-WTC-Progress-Newsletter.pdf "Construction Progress Around the WTC Site"]. World Trade Center Progress newsletter, February 2011, Panynj.gov, accessed May 12, 2011 On May 12, 2011, plans led to install prismatic glass on the building's base were cancelled due to technical problems.[http://www.huffingtonpost.com/2011/05/12/world-trade-center-update_n_860992.html "Prismatic glass facade for WTC tower scrapped"]. Huffington Post, May 12, 2011. Retrieved June 19, 2011.

By June 15, 2011, One World Trade Center had reached the 70th floor, the glass facade installation had reached the 45th floor, and concrete flooring had been installed up to the 63rd.[http://www.panynj.gov/wtcprogress/progress.html World Trade Center Growing This Summer] {{Webarchive|url=https://web.archive.org/web/20111023004622/http://www.panynj.gov/wtcprogress/progress.html |date=2011-10-23 }}. "World Trade Center Growing This Summer" Retrieved June 1, 2011 On August 1, 2011, concrete workers and carpenters at the tower walked off the job one month after their labor contract had expired. The workers returned to work on August 3.[https://archive.today/20120909075219/http://www.ny1.com/content/top_stories/144352/concrete-workers-end-strike-at-wtc-site "Concrete Workers End Strike at WTC Site"]. NY1 News and Time Warner Cable Inc., August 4, 2011Joseloff, Matt and Stephen Nessen.[https://archive.today/20130416063456/http://www.wnyc.org/blogs/wnyc-news-blog/2011/aug/02/world-trade-center-workers-walk-job-second-day/ "World Trade Center Workers Walk Off Job for Second Day"]. WNYC News Blog, New York Public Radio, August 2, 2011

Construction slowed from January to February 2012 due to an unseasonably warm winter which caused high winds and icing conditions to form on top of the structure making it hazardous for the construction workers. Further delays were caused by financial problems with a steel supplier which slowed delivery of steel beams to One World Trade Center. It took over two months to complete the 92nd floor.{{cite web|url=http://www.crainsnewyork.com/article/20120129/REAL_ESTATE/301299972|title=WTC money woes resurface|author=Theresa Agovino|date=29 January 2012|work=Crain's New York Business}} With the weather improving in March and financial issues being resolved, the construction progressed above the 92nd floor. 1 WTC later surpassed the Bank of America Tower as the 3rd tallest in the city.{{cite news |url=https://www.bloomberg.com/slideshow/2012-05-01/one-world-trade-center-rises.html | work=Bloomberg | title=One World Trade}} In May 2012, it was announced that the 408-foot spire originally planned to adorn the top of One World Trade will have its radome stripped, revealing the mast of the same height. This announcement was withdrawn in September 2013. On November 12, 2013, One World Trade Center was given the official height by the CTBUH as the Tallest Building in the Northeastern United States. (surpassing the Willis Tower amongst much debate), eleventh tallest in the world, and was given the title of the World's Tallest Spire. (Burj Khalifa, the tallest building in the world, has a shorter spire, despite starting at a higher altitude.){{cite web|title=One World Trade Center Named Tallest US Building|first=David B.|last=Caruso|date=November 12, 2013|agency=Associated Press|work=ABC News|url=https://abcnews.go.com/US/wireStory/committee-ny-tower-tallest-building-20859063|archive-url=https://web.archive.org/web/20131115015107/https://abcnews.go.com/US/wireStory/committee-ny-tower-tallest-building-20859063|archive-date=November 15, 2013}}{{cite news|url=https://www.chicagotribune.com/2013/11/12/tallest-building-ruling-willis-tower-loses-to-one-world-trade-center/ | work=Chicago Tribune | title=Tallest building ruling: Willis Tower loses to One World Trade Center | date=November 12, 2013}}{{cite news|url=https://www.nytimes.com/2013/11/13/nyregion/one-world-trade-center-is-ruled-tallest-building-in-us.html?_r=0 | work=The New York Times | first1=Patrick | last1=McGeehan | first2=Charles V. | last2=Bagli | title=1 World Trade Center Is Ruled Tallest Building in the U.S | date=November 12, 2013}}

On June 21, 2012, One World Trade Center Topped out at roof level, leaving the building to rank around 30th place among all other skyscrapers. Construction slowed again from late June till mid July due to high temperatures which caused the building to remain at roof level, leading to a delay in the installation of the antenna spire. With temperatures easing by July 16, construction crews began installing parapet steel at the top of 1 WTC. On July 18, the first node steel was installed.{{cite web|url=http://m.flickr.com/#/photos/28030045@N06/7597586924/sizes/m/|title=Flickr Photo of Parapet and Node Steel|date=7 July 2012|work=flickr.com}}{{cite web|url=http://forum.skyscraperpage.com/showthread.php?t=123628&page=1255 |title=NEW YORK | One World Trade Center | 1,787' Pinnacle / 1,373' Roof | 108 FLOORS – Page 1255 – SkyscraperPage Forum |publisher=Forum.skyscraperpage.com |access-date=2013-01-24}} On July 31, 2012, all corner parapet columns, also called "node steel", were installed around the perimeter of the tower. A special beam, signed by the U.S. President Barack Obama, local officials and the construction workers, was raised on August 2, 2012. A ceremony was held for the occasion, but officials denied that it was considered a topping-out ceremony.{{cite web |url=https://abc7ny.com/archive/8758931/ |title=Special beam set to be raised at One World Trade Center | 7online.com |publisher=Abclocal.go.com |date=2012-08-02 |access-date=2013-01-24 |archive-url=https://web.archive.org/web/20121017022950/http://abclocal.go.com/wabc/story?section=news%2Flocal%2Fnew_york&id=8758931 |archive-date=2012-10-17 |url-status=live }} By August 10, 2012, concrete flooring had been completed to the 93rd story of the tower, One World Trade Center had risen to the 105th floor and glass installation was at the 82nd floor.{{cite web |url=http://www.lowermanhattan.info/construction/project_updates/freedom_tower_26204.aspx |title=Lower Manhattan : 1 World Trade Center |publisher=Lowermanhattan.info |access-date=2013-01-24 |url-status=dead |archive-url=https://web.archive.org/web/20111216172827/http://www.lowermanhattan.info/construction/project_updates/freedom_tower_26204.aspx |archive-date=2011-12-16 }} The building was structurally topped out on August 30, 2012 when the last of the spandrel beams were installed between the parapet columns.{{cite news |last=Higgs |first=Larry |title=One World Trade Center steel skeleton completed |publisher=Asbury Park Press |date=August 30, 2012 |url=http://www.app.com/article/20120830/NJNEWS/308300075/One-World-Trade-Center-steel-skeleton-completed?nclick_check=1 |access-date=2012-08-30 |archive-date=2013-01-01 |archive-url=https://archive.today/20130101225738/http://www.app.com/article/20120830/NJNEWS/308300075/One-World-Trade-Center-steel-skeleton-completed?gcheck=1&nclick_check=1 |url-status=dead }}

In late 2012, the workers were installing a temporary steel framework at the top of the tower to support the 408-foot (124 m) steel spire during assembly. The spire was fabricated as 16 separate sections at a factory near Montreal, Quebec, Canada and was transported by barge to New York City in mid-November. Just after Thanksgiving, crews began to transport the spire segments one by one to the WTC site. Upon reaching the WTC site, the spire sections were being assembled, piece by piece, at the top of 1 WTC.

On December 12, 2012, the first of nine pieces of the spire were lifted to the 104th floor. Another nine smaller pieces were trucked in from Montreal.{{cite web |url=http://www.lowermanhattan.info/news/1_wtc_spire_preparations_50218.aspx |title=Lower Manhattan : News | 1 WTC Spire on Its Way to the Top |publisher=Lowermanhattan.info |date=2012-09-11 |access-date=2013-01-24 |url-status=dead |archive-url=https://web.archive.org/web/20120928040848/http://www.lowermanhattan.info/news/1_wtc_spire_preparations_50218.aspx |archive-date=2012-09-28 }}

On May 10, 2013, the last two sections of the building's spire were installed making it the tallest building in the Western Hemisphere, and the 3rd tallest building in the world.{{cite news|last= Newman|first=Andy|title=Crowning 1 World Trade Center|work=The New York Times|date=May 2, 2013|url=http://cityroom.blogs.nytimes.com/2013/05/02/crowning-1-world-trade-center/|access-date=2013-05-02}}

The exterior elevator began removal in late January 2014 and concluded in early June 2014. Base cladding began in February 2013 and concluded in June 2014. Work began on the construction of the plaza surrounding the building in late 2013 and interior work was finished in November 2014.{{citation needed|date=April 2014}}

The building opened in November 3, 2014, to 175 employees of publisher Condé Nast.{{cite news|last=Barron|first=James|title=1 World Trade Center, a Pillar of Resilience, Is Open for Business|work=The New York Times|date=November 3, 2014|url=https://www.nytimes.com/2014/11/04/nyregion/first-tenant-of-1-world-trade-center-arrives-highlighting-lower-manhattans-renewal.html}}

On May 29, 2015, the One World Observatory, at the tower's top, opened to the public.{{cite web | url=http://www.nydailynews.com/new-york/observation-deck-wtc-freedom-tower-opens-29-article-1.2176323 | title=Observation deck at World Trade Center's Freedom Tower to open May 29 | work=NY Daily News | date=April 7, 2015 | access-date=April 8, 2015 | author=Corky Siemaszko}}

File:Freedomtower oct2006.jpg|Concrete construction, as of October 7, 2006

File:Freedom tower 2007-mar26.jpg|Steel installation, as of March 26, 2007

File:Wtcsite-2007oct7.jpg|Foundation construction, as of October 7, 2007

File:Freedom tower construction.jpg|Construction progress, as of January 21, 2008

File:Wtcsite-20080420a.jpg|Concrete foundation, as of April 20, 2008

File:FreedomTowerFromWTC7.JPG|Construction progress, as of September 10, 2008

File:OneWTC-Construction-Feb2009.jpg|One WTC above street level, as of February 28, 2009.

File:Freedom tower July 2009.jpg|One WTC viewed from street level on July 29, 2009.

File:Last column.jpg|The final lobby column being installed on October 31, 2009.

File:Freedomtowerdecember.jpg| Construction reaching the 17th floor, as of December 10, 2009.

File:1WTC Construction march10.jpeg|View from the World Financial Center, March 8, 2010.

File:World Trade Center site 2010.jpg|Construction progress, as of April 2010.

File:One World Trade Center Construction 051110.JPG|View from Church Street, May 11, 2010, as steel tops the 24th floor.

File:One WTC Construction 10 June.jpg|View from the PATH station entrance, June 10, 2010, as steel tops the 26th floor.

File:One WTC From W Hotel 7-28-10.JPG|Construction work as of July 28, 2010, as steel reached the 30th floor.

File:One WTC tower construction progress Sept 2010.JPG|Construction as of September 28, 2010, as steel reached the 42nd floor.

File:11.10.10FreedomTowerByLuigiNovi1.jpg|One World Trade Center on November 10, 2010, reaching the 48th floor.

File:12.19.10FreedomTowerByLuigiNovi3.jpg|December 19, 2010, after steel reached the 52nd floor; the halfway point.

File:January13thWTCProgress.JPG|As of January 13, 2011, with the glass facade clearly visible.

File:WTC JLayne.jpg|View from West Street as of February 5, 2011. 7 World Trade Center is visible in the background on the right. Steel tops the 56th floor.

File:WTCMarch19.JPG|March 19, 2011, as construction reaches the 60th floor.

File:Wtc05022011.jpg|Progress as of May 2, 2011, Steel is up to the 64th floor and glass is at the 36th floor.

File:WTCJune1st1.JPG|June 1, 2011.

File:OneWTCAug16.jpg|August 16, 2011.

File:WTC Progress Sep17.jpg|Progress as of September 17, 2011. Steel is at 83 floors, glass at 58 floors and concrete at the 72nd floor.

File:Oct2011FreedomTower.JPG|Progress as of October 13, 2011. Steel is at 86 floors, glass is at 60 floors and concrete is at 76 floors.

File:WTC1115.jpg|Progress as of November 15, 2011. Steel is past 89 floors, glass is at the 63rd floor, and concrete is past the 80th floor.

File:1WTC DEC 23, 2011.jpg|Progress as of December 23, 2011, pictured from the corner of Liberty and Greenwich Street. Steel is up to 92 floors, glass is up to 68 floors, and concrete is up to 84 floors.

File:1WTC28Jan2012.png|One World Trade Center on January 28, 2012.

File:1WTC13March2012.JPG|One World Trade Center on March 13, 2012.

File:1WTC13April2012.JPG|One World Trade Center on April 13, 2012. Steel is up to 100 floors, and glass is at 71.

File:WorldTradeCenter05282012.JPG|One World Trade Center as of May 27, 2012.

File:NYC 07 2012 One WTC 4063.JPG|One World Trade Center under construction on July 24, 2012.

File:NYC 08 2012 One TWC 4241.jpg|One World Trade Center on August 20, 2012.

File:One World Trade Center as of November 4, 2012.jpg|One World Trade Center on November 4, 2012.

File:1WTC-22feb13.jpg|One World Trade Center on February 22, 2013. The first two sections of the spire now in place.

File:One WTC from behind Brookfield Pl May 2013.jpg|One World Trade Center on May 1, 2013. Windows now reaching the top of the building.

File:One WTC Spire Completed.jpg|The spire beacon was installed on May 10, 2013, as seen here

File:One WTC 6.1.13.jpg|One WTC as of June 1, 2013

File:Freedom tower in costruzione, gennaio 2014.JPG|One WTC as of January 22, 2014

{{Reflist}}

{{Commons and category|One World Trade Center|Construction of One World Trade Center}}

• [http://www.panynj.gov/wtcprogress/live-camera.html Port Authority Live Camera] {{Webarchive|url=https://web.archive.org/web/20101227033736/http://www.panynj.gov/wtcprogress/live-camera.html |date=2010-12-27 }} of the construction

{{World Trade Center|state=collapsed}}

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