NEW YORK (TheStreet) -- Thirteen years after the 9/11 terrorist attacks, lower Manhattan looks very different.
The site of the new World Trade Center hosts the Freedom Tower -- the tallest building in the Western Hemisphere -- as well as a new National September 11 Memorial Museum, which opened in May 2014. Three years ago, on the 10th anniversary of the attacks, the National September 11 Memorial was dedicated to the nearly 3,000 victims and their families. It also pays tribute to the victims of the 1993 bombing of the World Trade Center.
In 2015, construction of the state-of-the art World Trade Center Transportation Hub is expected to be completed. Following completion, it is expected to serve more than 200,000 daily commuters and millions of visitors through 11 different subway lines, the PATH train and the Battery Park City Ferry Terminal, connecting visitors to the World Trade Center's Towers 1, 2, 3 and 4 and the World Financial Center, as well as shops and restaurants located on the main concourse.
On the anniversary of the event, TheStreet took a look at the vast changes that have taken place in and around the site of the WTC since the attacks on Sept. 11, 2001.
The Twin Towers as they were being constructed in 1971. The Port Authority chose lead architect Minoru Yamasaki and associate architects Emery Roth & Sons in 1962 to design the new buildings, according to the New York Times.
The former World Trade Center site and Battery Park were originally built on reclaimed land extending the border of lower Manhattan. An aerial view of the former World Trade Center and lower Manhattan, taken in June 1999.
The former Twin Towers were 110 floors each, reaching 1,368 and 1,362 feet for the respective North and South towers. The first tenants moved into the North Tower in December 1970. The first occupants of the South Tower followed in September 1971, according to the Web site of the Port Authority of New York & New Jersey. A ribbon cutting ceremony for the Twin Towers was held in April 1973.
The World Trade Center's famous sculpture, The Sphere created by German artist Fritz Koenig, was placed in the plaza in 1971 in time for the opening of the towers. It was severely damaged in the 9/11 attacks but remained intact. Six months following the attack, The Sphere was moved to Battery Park. It remains there today. This photo was taken in May 1977.
5 World Trade Center (seen at right) was one of the buildings that survived the attacks, but was demolished in 2002. It housed the famous "Survivor's Stairs" which served as an escape route for hundreds of employees. The staircase is now a part of the National September 11 Memorial & Museum.
The Marriott World Trade Center (seen in back) sat in between the former Twin Towers. Its formal address was 3 World Trade Center. Following the attacks, the hotel served as a staging area for New York City firefighters. The hotel was at full capacity at the time of attacks. The only part of the hotel not destroyed as a result of the towers collapsing was the south area of the remaining three floors.
The current site of the World Trade Center. To the left is the base of the Freedom Tower -- 1 World Trade Center. In the middle is the National September 11 Memorial, which features twin reflecting pools laid in the footprint of each former Twin Tower. It opened on the 10th anniversary of 9/11 attacks to the victim's families as a dedication ceremony for victims' families. It opened to the public on Sept. 12, 2011.
The reflecting pool of the South Tower. The memorial, titled "Reflecting Absence," was designed by architect Michael Arad and landscape architect Peter Walker. The design was selected from competition that included more than 5,000 entrants from 63 nations.
The rebuilt WTC site will feature a newly constructed transportation hub (far right). Designed by world-renowned Spanish architect Santiago Calatrava, the hub will rival Grand Central Terminal in size and will open in 2015.
"The WTC Transportation Hub's concourse will conveniently connect visitors to 11 different subway lines, the Port Authority Trans-Hudson (PATH) rail system, Battery Park City Ferry Terminal, the World Trade Center Memorial Site, WTC Towers 1, 2, 3, and 4, the World Financial Center and the Winter Garden. It will represent the most integrated network of underground pedestrian connections in New York City," according to the Web site of The Port Authority of New York & New Jersey.
Behind the reflecting pool of Tower One stands the World Financial Center, which was heavily damaged in the attacks. Parts of the complex have been reconstructed. In 2014, the complex was renamed Brookfield Place. It features both office space as well as restaurants and retail shops along the waterfront.
The Freedom Tower, One World Trade Center. With 104 floors, it stands as the tallest building in the Western Hemisphere at a record 1,776 feet, replacing the Willis Tower (commonly known as the Sears Tower) in Chicago, which stands at 1,451 feet. The building was designed by renowned architect David Childs, of Skidmore, Owings and Merrill. It serves as the centerpiece of the new World Trade Center site. The building is currently more than 55% leased, with publisher Conde Nast as its anchor tenant, according to the Port Authority of New York & New Jersey.
Surrounding each reflecting pools are the names of the more than 3,000 victims of the 9/11 attacks including those from the World Trade Center, the Pentagon and those from United Flight 93, which crashed in Shanksville, Pa., on its way to San Francisco. It also includes the names of the victims from the 1993 bombing of the WTC site.
Roses are placed on each victim's name when it is their birthday by the memorial's staff.
--Written by Laurie Kulikowski and Adam Leverone in New York.