U.S. President Barack Obama, first lady Michelle Obama, Vice President Joseph Biden, his wife Jill Biden, and White House staff listen to 'Taps' as they observe a moment of silence to mark the 12th anniversary of the 9/11 attacks September 11, 2013 on the South Lawn of the White House in Washington, DC.

The nation is commemorating the anniversary of the 2001 attacks which resulted in the deaths of nearly 3,000 people after two hijacked planes crashed into the World Trade Center, one into the Pentagon in Arlington, Virginia and one crash landed in Shanksville, Pennsylvania. The president is planning trips to the Pentagon, and take part in a service project to commemorate the National Day of Service and Remembrance.Do you remember where you were on that date?