The twin towers of the World Trade Center were more than just buildings. They were proof of New York's belief in itself. Built at a time when New York's future seemed uncertain, the towers restored confidence and helped bring a halt to the decline of lower Manhattan. Brash, glitzy, and grand, they quickly became symbols of New York.

Rockefeller Brainchild

The World Trade Center was conceived in the early 1960s by the Downtown-Lower Manhattan Development Association to revitalize the seedy “radio row” dominated by electronic stores. Chase Manhattan Bank chairman David Rockefeller, founder of the development association, and his brother, New York governor Nelson Rockefeller, pushed hard for the project, insisting it would benefit the entire city.

In 1962, the Port Authority of New York and New Jersey began plans to build the center. Minoru Yamasaki and Associates of Michigan was hired as architect. Eventually, Yamasaki decided on two huge towers. Critics charged that a modern monolith would rob New York of character, ruin the skyline, disrupt television reception, and strain city services. However, the project was approved and construction began in 1966.

In order to create the 16-acre World Trade Center site, five streets were closed off and 164 buildings were demolished. Construction required the excavation of more than 1.2 million cubic yards of earth, which was used to create 23.5 acres of land along the Hudson River in lower Manhattan. During peak construction periods, 3,500 people worked at the site. A total of 10,000 people worked on the towers; 60 died during its construction.

Instant Landmarks

The north tower was opened in Dec. 1970 and the south tower in Jan. 1972; they were dedicated in April 1973. They were the world's tallest buildings for only a short time, since the Sears Tower in Chicago was completed in May 1973. However, the towers were ranked as the fifth and sixth tallest buildings in the world at the time of their destruction on Sept. 11, 2001.

Four smaller buildings and a hotel, all built nearby around a central landscaped plaza, completed the complex. The mall at the World Trade Center, which was located immediately below the plaza, was the largest shopping mall in lower Manhattan. The six basements housed two subway stations and a stop on the PATH trains to New Jersey.

Some 50,000 people worked in the buildings, while another 200,000 visited or passed through each day. The top floor observation deck had 26,000 visitors daily, who could see for 45 mi on a clear day. From the ground, the towers were visible for at least 20 mi. The complex had its own zip code, 10048.

Previous Bombing

In 1993 terrorists drove a truck packed with 1,100 lbs of explosives into the basement parking garage at the World Trade Center. Despite the size of the blast—it left a crater 22 ft wide and five stories deep—only six people were killed and 1,000 injured. The towers were repaired, cleaned, and reopened in less than a month.

September 11, 2001

On the morning of September 11, 2001, terrorists from al-Qaeda hijacked four planes. Two were Boston-to-Los Angeles flights, which the hijackers diverted to New York City. At 8:45 a.m., American Airlines Flight 11 was flown into the north tower of the World Trade Center. Eighteen minutes later, United Airlines Flight 175 was flown into the south tower. Each plane was loaded with sufficient jet fuel for its intended cross-country trip, which ignited upon impact, creating intense fireballs in both towers and weakening the structural integrity of each. At 9:50 a.m., the affected floors of the south tower gave way; the upper floors collapsed onto the lower ones, destroying the tower and crushing everyone who was still inside it. At 10:29 a.m., the same happened to the north tower. 2,824 people were killed in the attacks, including hundreds of firefighters and other rescue workers.

(Of the other two hijacked planes, one was crashed into the Pentagon; the other crashed southeast of Pittsburgh, apparently as a result of its passengers fighting the hijackers. There were no survivors.)

Rebuilding Plans

In 2002, separate design contests were held for rebuilding the World Trade Center site and creating a memorial for the victims of the attacks. The first round of finalists for the site, unveiled in July 2002, were widely criticized as being too boring and having too much of an emphasis on office space, leading to a new round of finalists in December.

In February 2003, the Lower Manhattan Development Corporation, which was established by Governor Pataki to coordinate the various agencies and advisory committees involved in the rebuilding efforts, chose architect Daniel Libeskind's design for rebuilding the 16-acre site of the former World Trade Center. The design included a hanging garden, a memorial, a cultural center, and Freedom Tower, which would be a symbolic 1,776 feet tall from the ground to the top of its spire. This would make it taller than any building currently standing in the world. (The Burj Dubai skyscraper currently under construction in the United Arab Emirates is expected to be higher, however.)

In July 2003, David Childs was brought in as the new lead architect of Freedom Tower, although Libeskind remained in charge of designing the site in general. The two had different visions for the tower; a design combining the approaches of both architects was unveiled in December 2003. It would include wind turbines in its spire, designed to generate as much as 20% of the building's power.

On July 4, 2004, New York Governor Pataki, New Jersey Governor McGreevey, and New York City Mayor Bloomberg laid the cornerstone for Freedom Tower. The skyscraper, estimated to cost $1.5 billion, was expected to be ready for its first occupants by late 2008, while construction on the site in general was expected to last through 2015.

Just as construction was beginning, security concerns were raised, leading to a complete redesign of the tower. The new plans were released on June 29, 2005. The tower is to be moved further back from the street, and will have a cubic base the same size as each of the Twin Towers. The wind turbines have been eliminated. The design recalls that of the old buildings, while adding its own twists: starting with the square base, the tower's design moves to triangular forms, creating an octagon in the middle, and culminates in a square at the top, rotated 45 degrees from the base. A spire will rise a bit more than 400 feet beyond that, to retain the planned total height of 1,776 feet.

Work on excavating the foundation finally got underway in late April 2006. Refined plans were announced in June 2006, calling for glass prisms around a concrete base, to liven up the area while meeting security requirements. The tower is now planned to cost $2 billion, and be ready for occupants in 2011.

Design for World Trade Center Memorial Selected

The Lower Manhattan Development Corporation announced in January 2004 that architects Michael Arad and Peter Walker had won a competition to design the memorial to the people who died at the World Trade Center. There had been more than 5,000 entries in the competition.

The memorial, Reflecting Absence, would honor those who died at the World Trade Center in terrorist attacks on September 11, 2001, and February 26, 1993. In the 1993 tragedy, a truck bomb exploded in a garage in the north tower, killing six people and injuring more than a thousand.

Reflecting Absence, which will be built where the Twin Towers once stood, includes two shallow pools surrounded by leafy trees. The names of the victims would be etched in walls around the pools.

“In its powerful, yet simple articulation of the footprints of the Twin Towers, Reflecting Absence has made the gaping voids left by the towers' destruction the primary symbol of loss,” said Vartan Gregorian, who chaired the jury that chose the winner.

The memorial plans were redesigned in June 2006 due to security concerns, budgetary issues, and input from the victims' families. The central features—including the two pools, fed by waterfalls—will be retained. The names of those killed would be moved to the surrounding plaza, above ground.

Construction will begin in 2006, and the memorial is scheduled to open on Sept. 11, 2009.

Twin Towers Stats

—200,000 tons of steel

—425,000 cubic yards of concrete

—43,600 windows

—12,000 miles of electric cables

—198 miles of heating ducts

—23,000 fluorescent light bulbs

Each Tower

—110 floors

—208 ft by 208 ft at base

—1,368 ft high (north tower)

—1,362 ft high (south tower)

—Weighed 500,000 tons

—97 elevators for passengers, 6 for freight