I often go to Dunedin for many varied reasons, and one of the delights of every trip is a visit or two to the oldest botanical garden in New Zealand, which was established in 1863.
There are two parts of the Dunedin Botanic Garden, linked indiscernibly, known as the upper gardens and the lower gardens which merge nicely with the University of Otago campus. View Google Map
The initial garden was established on a site now occupied by the University but due to extensive flooding in 1868, the gardens were moved to their current site in 1869.