People in Memphis, Tennessee participated in the annual Martin Luther King Day march on Monday, to remember the African-American who led the mid-20th century Civil Rights Movement in the United States. /CFP Photo

US President Barack Obama and First Lady Michelle Obama (Back) helped finish a wall painting of Martin Luther King Jr. on January 16, also the national Martin Luther King Jr. Day. /CFP Photo

US President-elect Donald Trump on Monday met with Martin Luther King III, the eldest son of Martin Luther King Jr., at Trump Tower in New York City. /CFP Photo

US Senator Bernie Sanders (Right) attended the Martin Luther King Jr. Commemorative Service at Ebenezer Baptist Church in Atlanta, Georgia. /CFP Photo

Visitors gathered on Monday around the King Center in Atlanta, Georgia. Martin Luther King Jr. was a non-violent activist calling for racial equality during the Civil Rights Movement, but was shot dead by a protestor in 1968. Martin Luther King Jr. Day is an American federal holiday observed on the third Monday of January every year - close to King`s January 15 birthday - to honor the great man. /CFP Photo