Imagine that you are Willow the Wallaby, who has come from Australia to live in the Stone Zoo New England, and all day long you overhear young visitors talking about all the great sights to see in the Boston area. After making a list, wouldn't you want to hop over your fence and set off on a walkabout (that's what Australians call a walking tour)? Packing her notebook, pen and anything else she might need conveniently in her pouch, one foggy night,...