"I have a dream."

Fifty years ago today, some 250,000 Americans marched on Washington to hear those words. Martin Luther King, Jr., delivered an unforgettable speech from the steps of the Lincoln Memorial in Washington, D.C., as huge crowds of people — young, old, black, white — gathered to demonstrate their support for the civil rights movement.

Here, a selection of historic photos to honor the momentous anniversary of the March on Washington.

Members of the Congress of Racial Equality (CORE) set out before dawn on August 15 to walk the 230 miles to Washington, D.C. (AP Photo)

On the morning of Aug. 28, 1963, a father carrying his daughter head toward the rally. (Flip Schulke/CORBIS)

Civil Rights leaders lock arms as they move along Constitution Avenue. The Rev. Martin Luther King, Jr., is seventh from right. (Bettmann/CORBIS)

With the Capitol behind them, hundreds of marchers walk in formation along the Mall. (Flip Schulke/CORBIS)

Military policemen line up along the Washington Monument grounds. (AP Photo)

Crowds gather around the reflecting pool. (AP Photo)

Demonstrators pack the area in front of the Washington Monument as they await the start of the ceremonies. (Bettmann/CORBIS)

Activists hold hands in front of the Lincoln Memorial. (AP Photo/PBS, Courtesy Leonard Freed, Magnum Photos)

Martin Luther King, Jr., gives his "I Have a Dream" speech in front of the Lincoln Memorial. The widely quoted speech is among the most famous in U.S. history. (Bettmann/CORBIS)

The expansive crowds along the reflecting pools are photographed from above. (Flip Schulke/CORBIS)