Barack Obama has paid a "humbling" visit to the Robben Island prison cell in which Nelson Mandela was jailed for 18 years.
Accompanied by the first lady and his two daughters, the US president made the brief stop as part of an African tour.
He wrote in the guest book in the prison courtyard: "On behalf of our family, we're deeply humbled to stand where men of such courage faced down injustice and refused to yield.
"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."
Obama went on to make a keynote address at the University of Cape Town in which he payed tribute to Mandela and South Africa's wider achievements.