US President Barack Obama (R) hugs civil rights leader and Democratic Representative from Georgia John Lewis (2-R)after Lewis delivered remarks, as former US President Jimmy Carter (L) and former US President Bill Clinton (2-L) look on, during the 'Let Freedom Ring' commemoration event at the Lincoln Memorial in Washington DC, USA, 28 August 2013. The event was held to commemorate the 50th anniversary of the 28 August 1963 March on Washington led by the late Dr. Martin Luther King Jr., where he famously gave his 'I Have a Dream' speech.<br /> Credit: Michael Reynolds / Pool via CNP