Solemn memorials are being held in New York, Washington and Pennsylvania among other places to honor the victims of the September 11, 2001 terror attacks.
September 11 Anniversary

1
Civil War re-enactor Cpl. Robert Fuller Houston with the 3rd Regiment Infantry, lowers his head during a prayer at a ceremony, Sept. 11, 2013, marking the 12th anniversary of the 9/11 terrorist attacks at the Betsy Ross House in Philadelphia.

2
Riot police advance on a pro-democracy protest encampment in the Mong Kok district of Hong Kong early, Oct. 19, 2014.

3
Detroit Fire Department Lt. Gerod Funderburg rings a bell during a ceremony in Detroit, Sept. 11, 2013, marking the 12th anniversary of the 9/11 terrorist attacks.

4
Red roses are placed next to names of victims of the Sept. 11, 2001 terrorist attacks on the U.S. at a memorial site during a ceremony marking the 12th anniversary of 9/11 outside Jerusalem, Sept. 11, 2013.