Within the city of Johannesburg, there is a wide selection of sights and attractions to keep tourists busy, and some of the most popular are the Gold Reef City theme park, which has some great rides, the Museum Africa. Which has displays taking in the rich history of the city and its surrounding area.
If you're feeling daring, visit the Soweto (South-West-Township) area outside the city, it is an eye-opening, and often harrowing experience to see the poverty, but crime is endemic, and tourists are sometimes targeted. If you do visit Soweto, you should ensure that you do not wear any jewellery, carry very little cash, and take a guide with you.