Obama and his family spent Sunday at the Robben Island prison where Nelson Mandela served the majority of his 27-year jail sentence.
Their guide was Ahmed Kathrada, one of the former South African president's cellblock mates. Obama was silent as he examined Mandela's austere cell. It was here in the prison's damp confines that Mandela contracted Tuberculosis, and the lung infections that would plague him for most of his life.
The first family also saw the lime quarry where he toiled for years, fulfilling the "hard labor" portion of his sentence.
Before leaving, the Obamas signed the prison guest book.
"On behalf of our family we're deeply humbled to stand where men of such courage faced down injustice and refused to yield."
Nelson Mandela spent 18 of his 27 year prison sentence at Robben Island before becoming South Africa's first black president.