The World Remembers Mandela: Global Leaders Arrive In South Africa as 100,000 Gather In Soweto For Historic Memorial Service (PHOTOS)

World leaders have gathered in Johannesburg to pay tribute to Nelson Mandela at a memorial service for the former president of South Africa, five days after he died at the age of 95. Barack Obama was pictured arriving after a 17-hour flight from Washington on board Air Force One, during which he rode with his wife Michelle, former President George W. Bush, Laura Bush, and Hillary Clinton.