Why was 9/11 an important day in history?

I'm assuming you already know? On the 11th of September 2001 planes (hijacked and then piloted by terrorists) flew into the world trade centre. (Two iconic buildings in the New York skyline). People were killed, many people. The buildings collapsed, causing even more damage. It was a tragic day.

9/11 is so important i n history today because they was not only known to be the tallest buildings or twin tower they were the WTC (World Trade Center ) plus they were mostly filled with financial people . Trade was conducted with foreign countries, and we held meetings with foreign political leaders there...More importantly however, the towers stood for a meaning of strength, and connection for both our country, and the rest of the world. But once the planes hit the building everything was destroyed and people lost lives .