A highlight of Jo'burg's northern suburbs is Liliesleaf Farm. This was the secret headquarters of the ANC (African National Congress) from 1961 until a dramatic raid in 1963 that saw the capture of several of the organisation's leaders including Nelson Mandela. Free tours provide all the background, but you can also explore at your own pace, learning the story of South Africa’s liberation struggle through a series of high-tech, interactive exhibits.
There's also the very pleasant Cedric's Cafe at the museum should you plan to make a longer visit here.