The Royal Tasmanian Botanical Gardens, also referred to as RTBG, is located in Hobart, Tasmania, Australia and was a highlight of my time there. The Red Decker Sightseeing bus tour includes a stop at the gardens. This is the second oldest garden in Australia and dates to the early 1800s. The gardens include 35 acres of beautiful plants, so be sure to allow plenty of time. I visited in April, 2011, which is autumn there, and the colors were spectacular.
There are several restaurants there as well, where you can recharge after wandering through the gardens.
Have you visited the RTBG? If so, I would love to hear about your time there.