In 1983, Mitchell/Giurgola & Thorp, commissioned the forecourt mosaic, "Possum and Wallaby Dreaming", which Aboriginal Australian artist Michael Nelson Jagamarra, of Papunya, Northern Territory, based on his painting of the same name. The mosaic shows "a gathering of a large group of people from the kangaroo, wallaby and goanna ancestors are meeting to talk and to enact ceremonial obligations. The work derives from the sand-painting tradition of the Warlpiri people, and has complex layers of meaning known only to Warlpiri elders". Three stonemasons took 18 months to two years to hand-cut the 90,000 granite setts which were used in the artwork. The mosaic was digitised in April 2019 from a series of photographs taken from five metres above the artwork.