(VOVworld)- Thousands of people gathered in Johannesburg on Tuesday for Nelson Mandela's memorial service, which was held at the FNB stadium, where Mandela appeared before the public for the last time. The memorial service is the biggest gathering of world leaders in recent years. The attendees will hear a speech by South African President Jacob Zuma and condolences from world leaders including UN Secretary General Ban Ki Moon, US President Barak Obama, Brazilian President Dilma Rousseff and Cuban President Raul Castro. The late South African President Nelson Mandela died at 95 last week. South Africa is holding a series of activities to pay tribute to Nelson Mandela before the mourning service to be held on December 15^th.