CBC News Indepth: September 11

As a terrorist target, it's hard to find a more obvious and enticing symbol of America: the World Trade Center was one of the tallest buildings in the U.S., anchored the country's financial district, and was a New York icon.

That goes some way to explaining why the horrific attack of September 11, 2001, wasn't the first on the twin towers.

On Feb 26, 1993, Ramzi Ahmed Yousef and five others successfully conspired to detonate a car bomb in the bowels of the Center's north tower.

According to testimony at Yousef's 1997 trial, the men rented a yellow Ryder van and parked it in the garage of the 110-storey building. Inside was a specially crafted wooden box which housed the terrorists' deadly payload.

During his trial, Yousef said the box was placed in the van in such a way to maximize the bomb's impact.

He and his colleagues planned for the blast to shear the Trade Centre's support beams, causing one tower to topple into the other.

QUICKFACTS: THE WORLD TRADE CENTER

Erected in 1971 by the Port Authority of New York
Was located in Lower Manhattan, the largest financial hub in the world.
Occupied an area roughly as big as a small farm (16 acres)
Each tower was 110 stories
Envisioned as place to concentrate world trade services in order to facilitate trade between nations
Were the second tallest buildings in the United States. Only Chicago's Sears Tower was taller.
Accommodated more than 55,000 workers.
An estimated 80,000 visitors took in the building per day.
It took over eight months to clear the site after the September 11 attacks.
On March 13, 2006, construction officially began on the WTC Memorial and Museum.
A new office complex is to be rebuilt on the site of One World Trade Centre. The primary edifice will be a 1,776 ft building called Freedom Tower. Once completed it will be the tallest building in America. The groundbreaking for Freedom Tower took place on April 27, 2006.
Seven World Trade Center was the first tower to be rebuilt. It reopened on May 23, 2006.

Yousef told investigators he hoped the attack would murder 250,000 Americans in retaliation for the U.S.' continued support of Israel.

According to U.S. secret service agent Brian Parr, Yousef predicted the high death count would shock the United States into realizing it was at war.

Yousef also told Parr that his group was funded by "family" and "friends." While Yousef didn't claim to be formally attached to any larger terrorist group, many suspected the terrorists were working with former Saudi businessman Osama bin Laden.

Yousef and his conspirators were found guilty of engaging in a "war of urban terrorism" and sentenced to 240 years in prison with no hope for parole.

Security ground at the towers was tightened to the point where it was some of the strictest in the United States,

Still no one could have prepared, or predicted, an act of terrorism of the method and magnitude which took place on September 11.

The World Trade Center complex included seven buildings, all of which were destroyed. One World Trade Center (North Tower), Two World Trade Center (South Tower) and Seven World Trade Center collapsed. As the North and South Towers fell, they crushed Three World Trade Center (Marriott Hotel). Four, Five and Six World Trade Center were irreparably damaged and ultimately torn down.

"A second occurrence is just beyond belief," said Ira Furber, former National Transportation Safety Board spokesman.

"It's just sick. It just shows how vulnerable we really are," said Keith Meyers, 39, of Ohio. "It kind of makes you want to go home and spend time with your family. It puts everything in perspective."