As an example, let's take central park.  It's widely acknowledged as a great boon to city morale, as parks frequently are, but the largest wild animals in central park at any time are invariably human beings.  Anything else of even a similar size must be domesticated.  Despite the wonderful infrastructure of New York City, it is unlikely that at any time in the near future people will be going to mid-town Manhattan to watch wolves hunting deer, nor do I believe that such a thing would be a healthy aspect of city life.  To get true wildness, it's probably a good idea to leave the city.  

The territory around the city would be wild (with transportation to other cities and densely populated areas that did not interfere with ground based movement) and people would be trained in the city to live out there as part of their education, or by food-forager advocates supported by their own communities outside the city, and training for city life would also be freely available.