Why did the terrorists choose the World Trade Centre and the Pentagon as targets for the September 11 Attacks and what year did it happen?

The September 11 Attacks occurred in year 2001.

The World Trade Centre and the Pentagon were the iconic landmarks of U.S.A. and they were used for very private activities of America such as military and many more. Moreover, the World Trade Centre towers were the tallest buildings in New York and were easy to spot and strike. The Pentagon was also destroyed on this day as this day was chosen for the groundbreaking ceremony in 1941, 60 years before the crash! They wanted this occasion of celebration to turn into a mourning ceremony, which were the main objectives of the Al-Qaeda Terrorist Organization. There was another plane that was hijacked, which its target was assumed to be either the United States Capitol or the White House, crashed near Shanksville, Pennsylvania, and the buildings made a narrow escape from the verge of destruction. The U.S. Capitol is a very important building which is rich in history. It was constructed in 1793 and major events such as the presidential inaugurations, Independence Day and Americans lying in state (death of important figures such as Presidents and Senators of America) have been held there. The White House is also a very important place too. It was constructed in 1792, and it is the place where the President of America lives and works! So, the ulterior motive of these terrorists are just to, as the name suggests, terrorize people and destroy historical and iconic buildings, killing innocents in the process.