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
Billionaire Microsoft co-founder Paul Allen has claimed discovery of the Japanese battleship Musashi that was sunk by the US Navy in 1945.
Friday will be mostly dry with sunny spells for much of the UK. Temperatures will be mild across the country.
Some famous Liberal Democrat names will be fighting for their political lives in the election, now just over two months away.