The Royal Botanic Gardens are located in Sydney, Australia and cover about 80 acres. They were founded in 1816 by Governor Macquarie, and were originally part of his estate.
Today, there are several gardens located on the property: a Pyramid greenhouse, which houses tropical displays, a rose garden, and herb garden, a cactus garden, and an oriental garden. There's also a lovely pond which is a perfect setting for a picnic.
One interesting note about the garden is that it was home to a colony of 22,000 flying foxes - a type of fruit bat. These little guys were causing quite a problem, so in 2011, a plan was implemented to remove the bats. I don't know how that worked. If you go, just keep an eye out for flying foxes.
The garden is open daily from dawn to dusk. Admission is free.