Thanks to Urbanartcore (http://www.urbanartcore.eu) I discovered Steve Duncan; an urban explorer, photogrpaher and historian. With the aid of videographer Andrew Wonder, the video below documents 4 journeys undertaken by them both into the underworld of New York City. The result is footage that is, simply put, extraordinary. If you can make 30 minutes in your day to sit and watch this, you will not regret it.
For those of us not cut out for the extreme adrenalin hit this sort of activity must provide, it serves up a diluted version we can all enjoy.