One World Trade Center is officially open for business. Take a look at New York's World Trade Center site before and after the Sept. 11 attacks.
The World Trade Center towers are seen from Church Street south during their final phase of construction, December 1970.
New York commuters walk to work, March 1, 1993, as business resumed in the Wall Street area of the city following the bombing in the World Trade Center.
The lower Manhattan skyline with the World Trade Center towers at center, Aug. 30, 2001, a few days before the Sept. 11 terrorist attacks.
United Flight 175 flies toward the south tower of the World Trade Center in New York as the north tower burns after being hit by American Flight 11 a short time earlier, Sept. 11, 2001.
The remaining tower of New York's World Trade Center dissolves in a cloud of dust and debris about a half hour after the first twin tower collapsed, Sept. 11, 2001.
Firemen carry an injured man from the World Trade Center after both towers collapsed after planes crashed into the buildings in New York on Sept. 11, 2001.
Workers walk near the wreckage of the World Trade Center in New York City, Sept. 12, 2001.
A crane lifts rubble from the ruins of the World Trade Center in New York, Oct. 12, 2001.
Cleanup and recovery work continues at ground zero site in New York on March 6, 2002.
Some of the thousands of handwritten messages on a hand rail on the public viewing platform overlooking ground zero in New York, March 6, 2002.
Jack Beyer, founding partner of Beyer Blinder Belle Architects & Planners, talks about the six conceptual plans for the World Trade Center site as they are revealed by the Port Authority of New York and New Jersey and the Lower Manhattan Development Corporation, in New York on July 16, 2002.
The cornerstone for the Freedom Tower, the 1,776 foot-tall building that will be built on the site, sits in place after a being unveiled during a ceremony at the base of the ground zero site of the former World Trade center in New York, July 4, 2004. The cornerstone is inscribed "To honor and remember those who lost their lives on September 11, 2001 and as a tribute to the enduring spirit of freedom, July Fourth 2004."
Developer Larry Silverstein (front row, 3rd L), New York Mayor Michael Bloomberg (front row, 2nd R) and New York State Governor George Pataki (back row, 2nd L) watch as the first construction equipment enter the World Trade Center Site to begin construction on the Freedom Tower in New York April 27, 2006.
World Trade Center developer Larry Silverstein pauses to look out a window down to ground zero from the 52nd floor of the new 7 World Trade Center tower in New York, May 8, 2006.
General view from the top of 7 World Trade Center at the site of the Freedom Tower at ground zero and Lower Manhattan in New York, July 19, 2006.
A woman looks out at the World Trade Center site beside a rendering of the Freedom Tower in New York, Sept. 10, 2007.
A general view of the World Trade Center construction site in New York, Sept. 8, 2009.
A woman uses her computer next to a model of the proposed memorial and buildings to be built at ground zero at the "Preview Site" for the National September 11 Memorial and Museum in New York, Aug. 27, 2009.
Construction workers continue building the walls of one of the memorial waterfalls at the World Trade Center site in New York, Oct. 26, 2010.
Construction work continues at the World Trade Center site in New York, Feb. 24, 2011.
Construction continues on One World Trade Center tower (R) at the World Trade Center site, March 17, 2011. When completed, One World Trade Center will reach 104 stories.
The memorial for victims of the 9-11 attacks at the site of the World Trade Center nears completion in New York on May 10, 2011. The two depressions mark the location of the original towers and will be reflecting pools.
The memorial plaza with the north and south pool waterfalls are seen through a window in the One World Trade Center tower on July 28, 2011.
A general view shows the south pool waterfall and the under construction One World Trade Center tower (rear) as work continues on the National September 11 Memorial and Museum (right) at the World Trade Center site on July 28, 2011.
Motorcyclists look at One World Trade Center upon arriving at ground zero in New York on Aug. 21, 2011.
Iron workers lifted the final piece of the spire to the top of the One World Trade Center in New York May 10, 2013. The piece raised the building to its full height of 1,776 feet and helped fill a void in the skyline left by the Sept. 11 attacks.
One World Trade Center officially opened for business on Nov. 3, 2014. Publisher Conde Nast was the first tenant, with 3,400 staffers filling 24 stories of the building.