Johannesburg - worthwhile?

As a first-time visitor to SA, I have an evening flight out of
Johannesburg when returning home. I hadn't planned on visiting
Jo-burg, but am considering arriving the night before my flight and
staying at a hotel by the airport. Would it be worthwhile to go into
the city during the day? What about safety? What is interesting to
see?

Thanks for replies.

Cheers,
Ann

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