Twenty-one years ago, on September 11th, 2001, al-Qaeda terrorists hijacked four planes, two of which hit the buildings of the World Trade Center skyscrapers in New York City. The third plane hit the Pentagon in Washington D.C., while the fourth plane was supposed to hit the Capitol, but crashed in Pennsylvania after the heroic action of passengers. Nearly three thousand people died that day, including six Poles. Americans came together today to honour the lives lost.