Twin Towers.

2001. September 11 when a series of four coordinated terrorist attacks launched by the Islamic terrorist group al-Qaeda upon the United States in New York City and Washington DC. Four passenger airplanes were hijacked by 19 al-Qaeda terrorists so they could be flown into buildings in suicide attacks.
Two of those planes, American Airlines Flight 11 and United Airlines Flight 175, were crashed into the North and South towers, of the World Trade Center complex in New York City. A third plane, American Airlines Flight 77, was crashed into the Pentagon (the headquarters of the United States Department of Defense).
The fourth plane, United Airlines Flight 93, was targeted at Washington, D.C. but crashed into a field near Shanksville, Pennsylvania.

Osama bin Laden's declaration of a holy war against the United States, In bin Laden's November 2002 "Letter to America", he explicitly stated that al-Qaeda's motives for the attacks: Support for the "attacks against Muslims" in Somalia, Russian "atrocities against Muslims" in Chechnya, Indian "oppression against Muslims" in Kashmir, the presence of U.S.A troops in Saudi Arabia and, finally, United States support to Israel.