Children play ball in front of a portrait of former president Nelson Mandela in a park in Soweto, South Africa, March 31, 2013.

Visitors to Nelson Mandela Square in Johannesburg pass beneath a statue of the former president, April 1, 2013.

Painted stones with well-wishes for Nelson Mandela in the garden outside his house in Houghton, Johannesburg, March 28, 2013.

Nelson Mandela and his then wife, Winnie, salute well-wishers as he leaves Victor Verster prison on February 11, 1990.

This undated photograph shows Nelson Mandela and his former wife, Winnie.

South African State President Frederik Willem de Klerk, left, and Deputy President of the African National Congress Nelson Mandela, right, prior to talks between the ANC and the South African government, Cape Town, May 2, 1990.

ANC leader and symbol of resistance to apartheid, Nelson Mandela, is seen as he gives the black power salute to the 120,000 ANC supporters in  Soweto's Soccer City stadium in Soweto, near Johannesburg, South Africa, Feb. 13, 1990.

Nelson Mandela attends a rally in this 1993 photo.

President Nelson Mandela and Britain's Prince Charles shake hands alongside members of the Spice Girls' Emma (L), and Gerri (R) at Mr. Mandela's residence November 1, 1997.

The former South African president, left, and his wife, Graca Machel, wave to the audience during a Live 8 concert in Johannesburg, South Africa, July 2, 2005.

Former South African president Nelson Mandela, center, followed by his grandson Mandla Mandela, rear right, arrives at the ceremony in Mvezo, South Africa, April 16, 2007.

Mandela poses for a photograph after receiving a torch to celebrate the African National Congress' centenary  in his home village, Qunu, in rural eastern South Africa, May 30, 2012.

School children read the history of former South African president Nelson Mandela written on a chalkboard, ahead of the opening of a container library by the Bill Clinton Foundation in celebration of Mandela Day, at a school in Qunu, July 17, 2012.

Children sing happy birthday in honor of former South African president Nelson Mandela during celebrations for Mandela's birthday in Mvezo, South Africa, July 18, 2012.