On Martin Luther King Jr.'s birthday, we remember the civil rights leader's most famous speech, and King's remarkable legacy. He was born on January 15, 1929, in Atlanta. He gave the "I Have a Dream" speech on Aug. 28, 1963 to 250,000 people who marched to the Lincoln Memorial in Washington D.C. In 1983, President Ronald Reagan signed a bill that created a federal holiday to honor King, celebrated on the third Monday in January.