Dr. Martin Luther King Jr. acknowledges the crowd at the Lincoln Memorial for his "I Have a Dream" speech during the March on Washington, D.C. in this Aug. 28, 1963 file photo.
A tourist points to the exact location where Rev. Martin Luther King Jr., gave his famous 'I Have a Dream' speech, at the Lincoln Memorial in Washington, Aug. 22, 2013.
U.S. Park Police watch over the Lincoln Memorial during sunrise early in the morning before the start of the ceremony honoring the 50th anniversary of the 1963 March on Washington, Aug. 24, 2013.
Marchers file towards their seats at the ceremony at the Lincoln Memorial honoring the 50th anniversary of the 1963 March on Washington, Aug. 24, 2013.