"I Have a Dream"
August 28, 1963: Martin Luther King Jr. delivers his most famous speech on the steps of the Lincoln Memorial as the statue of President Abraham Lincoln looks on.
The last prisoners to be held on Alcatraz Island file out as the federal penitentiary, known informally as The Rock, closes in 1963.
Jackie Kennedy watches from backstage as her husband debates Republican candidate Richard Nixon in the first-ever televised presidential debate, 1960.
The body of John F. Kennedy — the last president to die in office — lies in state in the U.S. Capitol on November 24, 1963, two days after he was assassinated.
A young Adolf Hitler cheers during a World War I rally in 1914. German historians have concluded that this photo was likely doctored by the Nazi party in 1932. It was published the day before the presidential election, amid questions about Hitler's patriotism.
German POWs watch footage of concentration camps shown to them by their American captors in 1945.
The models for Grant Wood's famous 1930 painting "American Gothic" — the artist's sister and their dentist — visit the work they inspired.
Norman Rockwell's "After the Prom" (1957) and the photographic study that preceded it.
The British ocean liner embarks on its fateful trip in April 1912. This is the last known photo of Titanic above water.
This is the iceberg widely believed to have sunk the Titanic on April 15, 1912. The smudges on the side are red and black paint.
The Spanish surrealist kisses Raquel Welch's hand after completing a portrait of her in 1965.
The Cuban dictator enjoys ice cream while visiting a American military camp.
One of only two known photos of the United States Supreme Court in session. It was shot in secret in 1932.
Spectators in the Palace of Versailles try to catch a glimpse of the signing of the treaty that marked the end of the war between Germany and the Allied Powers, on June 28, 1919.
The unknown protestor who came to be known as Tank Man stands his ground in Tiananmen Square, 1989.
Traffic blocks the road near the Brandenburg Gate as Germans cross freely from East to West after the fall of the Berlin Wall in 1989.
Visitors admire the view of downtown Manhattan from the observation deck of the Empire State Building on its opening day — May 1, 1931.
The Rockefeller Center Christmas tree makes its debut in 1931.
The "Hollywoodland" sign first appeared in 1923 as an advertisement for a housing development in the Hollywood Hills. Its last four letters — L-A-N-D — were removed in 1949 so that the sign would refer to the neighborhood rather than the development.
"Batman and Robin," a 15-part serial to be shown in movie theaters, is filmed in 1949.
Leo the Lion gets ready for his close-up as the Metro-Goldwyn-Mayer mascot is filmed for the studio's iconic logo in 1929.
The Beatles shoot the cover for their 1967 album, "Sgt. Pepper's Lonely Hearts Club Band."
Revelers rest after celebrating VJ Day — August 14, 1945 — in New York.
American soldiers celebrate the news of Japan's surrender in 1945.
The back of Hoover Dam, the last time it would be seen, in 1936, before it became submerged in water.
Foot traffic on opening day — May 27, 1937.
Mourners climb high to view the funeral procession of Mahatma Gandhi in 1948.
African-Americans demonstrate against the Vietnam War during a 1967 peace march in Harlem, New York.
Kathrine Switzer, the first woman to finish the Boston Marathon, keeps running, despite a race organizer's attempt to stop her in 1967.
Neil Armstrong smiles for Buzz Aldrin's camera, moments after his "one small step" on July 20, 1969.
Crowds gather at Woodstock Festival in Bethel, New York, for "three days of peace and music" in August 1969.