The World Trade Center

The remaining tower of New York's World Trade Center dissolves in a cloud of dust and debris about half an hour after the first tower collapsed. Photo: © Reuters/Ray Stubblebine 2001

Sept. 11, 2001 -- The World Trade Center, flattened by Tuesday's terrorist attack, was a cherished Manhattan landmark. Built in 1973, its twin, 110-story towers were 1,362 feet and 1,368 feet high. That made it more than 100 feet taller than the city's other towering landmark, the Empire State Building.

File photo shows sailors aboard the aircraft carrier U.S.S. John F. Kennedy as she steams into New York harbor May 22, 1996. REUTERS/Mike Segar-Files Photo: © Reuters

The Trade Center rested on a foundation containing a six-level basement, which required excavation of 1.2 million cubic yards of earth and rock, according to a building history published by the Engineering News-Record. Each tower was built 208 feet square. At the time of construction, the towers had the world's highest load-bearing walls, fashioned from some 200,000 pieces of steel, according to the building history.

However, the towers held the U.S. height record only briefly: Before the World Trade Center even was finished, construction was begun on Chicago's Sears Tower, which reached 1,450 feet.

The Center complex grew to include seven buildings on 16 acres, housing offices, restaurants, a hotel, an underground shopping mall, and an outdoor plaza. It was a popular destination for both tourists and locals: atop 2 World Center was the enclosed Top of the World observation deck offering panoramic views on all sides; and at the top of 1 World Trade Center was Windows on the World, one of the city's most popular restaurants.

In 1993, the World Trade Center earned an unwelcome notoriety that foreshadowed its fate today. On the morning of Feb. 26, 1993, an explosion rocked a commuter train station under the World Trade Center, killing six people and injuring more than 1,000 others. The explosion blew a hole 200 feet across in an underground parking garage, and caused more than $300 million in damage.

The source of the blast was determined to have been a bomb in a Ford van in the parking garage. Four men -- Mohammed Salameh, Nidal Ayyad, Ahmad Ajaj and Mahmud Abouhalima -- were tried in a long and complicated case in which the government called 207 witnesses and presented 1,003 pieces of evidence. In May 1994, the four were convicted on conspiracy, assault and explosives charges and sentenced to prison terms of 240 years each. In 1997, two more men were convicted: Ramzi Ahmed Yousef, for arranging the bombing and recruiting others to help; and Eyad Ismoil, for driving the van containing the bomb. Again, the prison sentences were 240 years each.

At the sentencing for the first four bombers -- in language that now seems eerily prophetic -- Judge Kevin Duffy berated the men for trying to make a bomb that would have done even more damage. "You might have succeeded in your nefarious plot to topple the north tower into the south tower," he said. "If that happened, we would have been dealing with tens of thousands of deaths."