This is the "Creatures of the Wollemi" aviary, and it's about ten years old now. Platypus are one of only three mammals displayed here - apart from a few reptiles the rest of the inhabitants are all birds.
Thank you Hix, I don't have my map or guidebook any longer, the online map doesn't give it, and neither do my notes. But I always love to get corrections and hints from locals, so I will change this now.
Did you see any platies in there? I stood for ages and only saw a duck, I had to go back to the platy house to see one. MUCH smaller than I had thought it would be,