There was an article on Urban Exploration in the Chronicle Herald, this was a surprise to me that there was such a interest in this type of exploring. I been doing this for years and typically like the more remote areas. Ironically it also causes problems like increased vandalizing due to the younger crowd being involved as well.
Some of the places in cities that people seam to be interested in are not really that big of a deal if you where to be a Building tech like HVAC or to do with Electrical.
A Canadian site listed was http://www.uer.ca