Kirstenbosch is the name of a famous botanical garden nestled at the foot of Table Mountain in Cape Town.
(It is on the eastern slopes of the mountain, not on the northern side normally depicted in the standard tourist snapshots).
(Kirstenbosch should not be confused with the similarly named suburb of Kirstenhof which lies some 10 km to the south.)
The garden is one of eight National Botanical Gardens covering five of South Africa's six different biomes. When Kirstenbosch, the most famous of the gardens, was founded in 1913 to preserve the country's unique flora, it was the first botanical garden in the world with this ethos.
Furthermore, what makes the Gardens so famous worldwide is that (with minor exceptions) only indigenous plants are cultivated.