There are some amazing urban agriculture initiatives around the world such as Brooklyn Grange Farm in New York. Using a large industrial rooftop [one acre] they operate a commercial farm, market etc, complete with amazing views to manhattan. Adelaide doesn't have many big roofs but maybe the Homemaker Centre or Bunnings would be a good start.
More about Brooklyn Grange:
Brooklyn Grange is a commercial organic farm located on New York City rooftops. We grow vegetables in the city and sell them to local people and businesses. The goal is to improve access to very good food, to connect city people more closely to farms and food production, and to make urban farming a viable enterprise and livelihood.
Although we function as a privately owned and operated enterprise, Brooklyn Grange is community oriented and open to the public. School groups, families and volunteers are welcome to visit, participate and learn. This is a green space that contributes to the overall health and quality of life of the community, bringing people together through green business and around good food.