It is believed that thousands of years ago, people lived on Robben Island. After the Dutch had settled at the Cape, the island was used mainly as a hospital for people with leprosy and the mentally and chronically ill because it was believed it was safer to keep them separated from the rest of the community. Patients were quarantined on part of the island, while the other part was used as a prison. During World War II, the Island was used mainly as a training camp. The island was officially turned into a maximum security prison in 1961.   It was used to incarcerate more than 3,000 political prisoners between 1961 and 1991, the most famous being Nelson Mandela. Since 1997, the island has been turned into a museum and heritage site.
References

Robben Island Museum History of Robben Island [online] Available at: www.robben-island.org.za [Accessed on 13 March 2012]|Places Robben Island [online] Available at: www.places.co.za [Accessed on 13 March 2012]