At Nelson Mandela's former prison, Barack Obama wrote how "deeply humbled" he was "to stand where men of such courage faced down injustice."
"The world is grateful for the heroes of Robben Island who remind us that no shackles or cells can match the strength of the human spirit."
President Obama wrote his comments in the visitors' book in the prison courtyard where he saw where Mandela worked and hid his draft of his book A Long Walk to Freedom.
More top news
Last minute preparations are going on at the Church of St Mary Magdalene where Princess Charlotte will be christened.
Princess Charlotte is being christened on Sunday at Sandringham in Norfolk in only her second public appearance since she was born.
Thunderstorms clear the North, leaving a dry and warm day with sunny spells.