Went to Tswaing on Saturday. It's one of the best preserved meteor craters in the world. About 200 000 years old.
Presumably, it has been used as a source for salt for whatever indigenous people were there at the time. There is certainly evidence of recent iron age usage. More recently, in the 1930's it was the focus of an industrialized salt extraction process. Luckily - whatever damage caused by salt mining is not visible within the crater - the African bush is quick to remove the marks of man.
50km north of Pretoria. You drive past Soshanguve, head up into a small nature reserve, take a small hike - and BAM. There it is. You really don't see what it is, until you walk up onto the rim.
