Johannesburg: Prime Minister Narendra Modi on Friday visited the Nelson Mandela Foundation here and paid tribute to the anti-apartheid icon. "Penultimate stop in Jo'burg, before community reception. PM pays a visit to the Nelson Mandela Foundation," External Affairs Ministry spokesperson Vikas Swarup tweeted along with photographs. Modi also met Ahmed Kathrada, Laloo Chiba, George Bezos and Ronnie Kasrils -- all comrades of Mandela. The Nelson Mandela Foundation served as the post-presidential office of Mandela and was established in 1999 after he stepped down as President of South Africa. It provided the base for his charitable work, covering a wide range of endeavours -- from building schools to HIV/AIDS work, from research into education in rural areas to peace and reconciliation interventions, according to the foundation's website. In 2004, the Foundation began its transition into an organisation focused on memory, dialogue and legacy work.. "A comprehensive refurbishment of the Foundation’s building provided it with an appropriate physical home, the Nelson Mandela Centre of Memory,” the website states. “The Centre was opened on November 18, 2013, three years to the day after Mr Mandela last used the building as his office.” Prior to this, Modi visited Constitution Hill, the site of South Africa's highest constitutional court and where Mahatma Gandhi was incarcerated, and paid floral tributes to the leader of India's freedom struggle. Later on Friday, he will address an Indian diaspora rally in Johannesburg before departing for Durban where his engagements are scheduled for Saturday. India and South Africa signed four agreements following delegation-level talks headed by Modi and South African President Jacob Zuma in Pretoria earlier on Friday. Modi arrived in South Africa from Mozambique on Thursday night on the second leg of his four-nation tour of Africa. This is his first visit to mainland Africa and is also the first prime ministerial visit from India to South Africa since the then Prime Minister Manmohan Singh arrived in 2013 for the G20 summit in Durban.