I was taken into the old Main Valley area last time I was at the zoo...tho i did visit when the area was fully operational. I cant think of anywhere else that has done this as a whole entity(rather than just an odd building or exhibit or so). Here in the UK, Belfast has the old zoo still just about intact next door but it is basically off show. It could be a very interesting concept
It's been out of use for over a decade now. I'm looking forward to seeing it again once they've finished! They've also repainted every building that needed it, using forensic paint matching. With the tram out for the foreseeable future, it'll give a really nice walk from the entrance to the main zoo.