President Barack Obama listens to former prisoner Ahmed Kathrada as he stands in former South African President Nelson Mandela’s cell during a tour of Robben Island Prison on Robben Island in Cape Town, South Africa, June 30, 2013.

President Barack Obama listens to former prisoner Ahmed Kathrada as he stands in former South African President Nelson Mandela's cell during a tour of Robben Island Prison on Robben Island in Cape Town, South Africa, June 30, 2013.