Rietvlei is a reserve situated between Johannesburg and Pretoria, They offer guided hiking, that is mainly because there are Rhinos in the reserve. But obviously they re not dangerous, our guides didn't carry any guns to protect us.
When we arrived at the start point we found lots of people ready to do the hike. We had to be divided into smaller groups allocated to a guide each. Our group had the talkative one. 
I asked a question and got so many answers that I did not dare to ask another question.
I can't remember how long the walk was, it was over by lunch time when we got to the Erasmus homestead. There we could relax and buy some lunch. We had to be ferried back to the starting point by ranger transport. Nice enough walk, I would do it again.