UN Secretary-General Kofi Annan (C) and his wife Nane pose 15 March 2006 with former South African President Nelson Mandela. Annan said he would spend his retirement doing grassroots work in Africa as South Africa's anti-apartheid hero Mandela hailed him as one of the best UN bosses ever.'When I retire. .. we (me and my wife) would want to devote some time to Africa to agriculture production and also to girls' education and women's empowerment. We'll move to Africa, we'll be in Ghana and also spend some time outside,' Annan told reporters after meeting Mandela in Johannesburg.