September 11, 2001

On September 11, 2001 , terrorists hijacked 4 airplanes and crashed them into the two towers of the World Trade Centre in New York and the Pentagon in Washington. The fourth jet crashed in Pennsylvania. About 3,000 people were killed and part of the Pentagon was destroyed. It was soon found out that Osama Bin Laden and his terrorist organization Al Qaeda had been behind the attacks.

The planes left the airports on the morning of September 11. Their originaldestination was California , so they had tons of fuel on board. Sometime after take-off , the terrorists took over the planes. Some of them had pilot training.

At 8:45 a.m. the first plane crashed into the north tower of the World Trade Centre. 20 minutes later, the second plane hit the south tower. Flames and smoke came out of the towers and the people who were working there tried to escape. About an hour after the attack both towers collapsed.

At about 9:40 a.m. a plane with 58 people on board crashed into the west side of the Pentagon, the country’s military headquarters in Washington. A part of the building collapsed and about 200 people were killed.

A fourth plane probably intended to crash into the White House or the Capitol, but a few passengers wanted to try to overcome the terrorists. The pilots lost control of the plane and it crashed into a field in Pennsylvania.

After the attack

After the attack on the USA, there was panic all over the country. The White House was evacuated and all air traffic over the continent was stopped. The stock exchange in New York stopped business and many tourist sights were closed down.

A month after the attack, the government gave the police and the FBI more power to hunt terrorists. New safety checks at airports were introduced and airlines started checking the baggage of their passengers more carefully.

The United States were convinced that Osama Bin Laden and his Al-Qaeda terrorist group were behind the attacks. In October, the U.S. attacked terrorist training camps in Afghanistan .

Why the Towers Collapsed

The two Boeing 767s that took off from Boston hat a lot of fuel with them because they were travelling to Los Angeles. Each jet had about 90,000 litres of fuel—about 2 tanker trucks full.

When the planes hit the towers they caused a massive fire that spread across many floors at the top of the buildings. Most likely,furniture, wood and paper in the offices began burning quickly , so that the fire could spread in a few seconds. The buildings did have an automatic sprinkler system, but this system was made to put out small fires.

The fire caused temperatures of over 1,000 °C , so that even the steel constructions in the buildings became weaker and weaker.

In the end, the top floors that remained undamaged were so heavy that the whole building collapsed. The World Trade Centre, however, withstood collapse long enough to save thousands of lives. About 99 % of the people in the lower floors could get out of the buildings before they fell.

Rebuilding Ground Zero

In the months after September 11, 2001 thousands of workers helped to clean up the place where the World Trade Centre once stood - known as Ground Zero. Many architects all over the world were called to present designs for rebuilding the site. In the future, glass towers will surround a memorialof September 11.

The World Trade Centre

The World Trade Centre was built by the American architect Minoru Yamasaki in the late 1960s and early 1970s. At their opening in 1972 they were the world's tallest buildings. They were over 400 metres tall and were made of 200,000 tons of steel. Each tower had 110 floors and 97 elevators.

Skyscrapers of this size have to be built in solid bedrock . In New York the solid rock starts at about 15 to 20 metres below the surface. When the builders of the WTC started digging they found out that after a few metres, water from the nearby Hudson River startedpouring in. So they dug out small boxes and put steel and concrete into them to give the building a firm stand.

When the World Trade Centre opened in 1973 the project was not very popular among New Yorkers. But as time went on and more and more companies started moving their offices to the twin towers they became more and more popular. The two towers also became famous through movies like “King Kong” and “Superman”.

Extreme sportsmen chose the WTC as the place to try out many stunts. Skydiversparachuted from the top of the towers, climbers went up to the top on the outside walls and a French acrobat walked from one tower to the other on a tightrope. Within a few years the towers were on postcards, T-shirts and ads.

The World Trade Centre also gave the New Yorkers another tourist attraction. On a clear day it was possible to see over 60 km in all directions. Visitors could travel up to the top of the North tower and eat in a luxurious restaurant called “Windows of the World”.

The Twin Towers were like a small city. Over 500 companies , including banks, law firms, television stations and airlines had their offices here and 50,000 people worked in the two buildings every day. On a typical day as many as 200,000 visitors from all over the world passed through the buildings.

In 1993 the World Trade Centre was the target of an earlier terrorist attack. A truck with 600 kg of explosives drove into the basementgarage of the building . When it exploded, a few stories were completely destroyed , but only 6 people were killed.