Most of the tour operators who take to Soweto will also run tours to Pretoria, the administrative capital of South Africa. Some 60km from Johannesburg, Pretoria can easily be seen in a morning.
Three significant sites encapsulate post-settler South African history. These are the Union Buildings designed by the colonial architect Herbert Baker and built in 1910 to mark the Union of South Africa; the Voortrekker Monument, concretization of white racist supremacy - and I am really not using jargon-speak here as this offensive ideology is overtly and unashamedly expressed in the whole monument; and post 1994 Freedom Park. Church Square was the equivalent of the town square in the late 19th Century while Kruger's house provides interesting re-constructions of the life and times of the Boer leader.
If you want to make a full day of your visit to Pretoria think of going to Cullinan, a quaint little town just twenty minutes' drive from Pretoria. There you can visit the Cullinan Diamond Mine, also known as the Premier Diamond Mine, where there are tours are available for entering the mine shaft, hoist room, big hole, and the display room.
Visiting Pretoria in November is an extra bonus, when the famous Jacaranda trees are in bloom with their purple flowers.