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The World Trade Center
was destroyed by terrorist attacks on September 11,
2001. The WTC was a complex of 7 buildings in Lower
Manhattan of which the Twin Towers were best known.
The two towers were different in height, the first one,
built in 1972 being 417 meters and the second one, finished
on year later measured 415 meters. The One World Trade
Center was the highest building in the world  until
1974, when the Sears Tower was
built in Chicao. When
destroyed, the Twin Towers still ranked in the top 10
of the highest buildings in the world and dominated
the skyline of lower Manhattan.
The World Trade center was a project started up in 1960
by David Rockefeller. The towers were sometimes nicknamed
David and Nelson, the Rockefeller brothers. The design
came from Minoru Yamasaki and Emery Roth & Sons. The
monolithic Twin Towers were never seen as great architecture,
but it certainly was a great engineering feat.
The Building never received the attention the Empire
State Building gets. But it first became world news
when, on friday Feb. 23, 1993 at 12:18, a bomb exploded
in the World Trade Center. The explosion, destroying
5 floors in the 110 story building, including the central
commando center, trapped about 50,000 people, killed
6 and wounded at least 1000 people. Moslem fundamentalist
have been convicted for the bombing.
 The
second time the WTC became world news was on the tragic
day September 11, 2001 when 2 hijacked planes crashed
into the twin towers. Not much later, the towers imploded.
More than 2,800 people died in the terrorist attack.
Even though the towers were built to withstand the impact
of a plane crash, the towers collapsed within 2 hours
of the initial impact. But an investigation into the
cause of the collapse of the towers found no structural
flaws or blunders. Some of the reasons of the collapse
are:
- the size of the planes: the Boeings that crashed into
the towers had a wing span of 156 ft, while the towers
were 'only' 209ft wide. The planes knocked out so many
columns in the building that the remaining columns could
no longer support the upper floors.
- the height of the impact: the planes crashed at altitudes
were it was almost impossible for firemen to contain
the fires. The internal sprinkler sytem was ineffective
if working at all, as several floors were wiped out.
The amount of kerosine intensified the fires to such
an extent that the steel eventually weakened and could
no longer support the top floors.
- The structure: after the upper floors collapsed, this
caused a domino effect as the floors below could not
support the collapsing top floors. This caused the whole
building to implode.
 The
implosion of the towers covered almost all of Lower
Manhattan in a dust cloud. Several days later, streets
around the WTC, also known as 'ground zero' were still
covered with dust. Many buildings in the neighborhood
of the attacked towers were either severely damaged
or collapsed. Among them One Liberty plaza and the World
Financial Center buildings. It took until May 30, 2002
before ground zero was officially cleared: 1,8 million
tons of rubble were removed in the process.
Time will tell if this tragedy becomes the Hindenburg
of the skyscrapers. The WTC 1 & 2 itself will not be
rebuilt, at least not as tall. Several projects for
world's tallest or 1000ft+ skyscrapers have already
been put on hold or have been scaled down.
Timeline of the WTC attack:
At 8:45 AM EDT, a hijacked Boeing 767, American Airlines
Flight 11 from Boston en route to Los Angeles hits the
north tower.
At 9:03 AM, a second hijacked Boeing 767, United Airlines
flight 175 from Boston en route to LA hits the south
tower.
At 9:50 AM, the top floors of the south tower collapse.
The whole tower collapses
At 10:28 AM, the top floors of the north tower implode,
bringing the rest of the building down.
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