The Twin Towers of the World Trade Center are just a memory now. But not one the nation will easily forget, ever after 15 years since the terror attack that brought them down. (IM Photo Collage)

Americans and others around the world honored the victims of the Sept. 11, 2001 terror attacks in New York City and Washington D.C. on the 15th anniversary of the tragic event. The nation is still at war with Islamic extremists but have suffered no major terror attacks since then.

The national day of mourning included ceremonies at Ground Zero in New York City as well as at the Pentagon in Washington, D.C.. The Defense Department headquarters was hit by one plane.

Two hijacked planes zeroed in on the Twin Towers in New York City, long a hated symbol of Islamic extremists. Each tower was hit causing a huge explosion. The buildings collapsed killing more then 2,700 people.

It was the largest single attack and loss of life on American soil since World War II, during the Japanese attack on Pearl Harbor in Hawaii.

The ceremonies were solemn. President Obama attended in Washington and presidential candidates Hillary Clinton and Donald Trump attended ceremonies in New York City.

Check out the photos below.

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America Pauses to Remember Sept. 11, 2001 (Click Photos to Enlarge!)