WASHINGTON (AP) — Oprah Winfrey, Jamie Foxx and Forest Whitaker are among the celebrities joining three presidents this week to mark the 50th anniversary of the March on Washington.

Soledad O’Brien and Hill Harper will host the “Let Freedom Ring” commemoration of Martin Luther King Jr.’s “I Have a Dream speech on Wednesday. President Barack Obama and former presidents Bill Clinton and Jimmy Carter are also joining the tribute at the Lincoln Memorial.