This is a post in progress. I know Canada and the US are part of the world but for me it is easier to sort them this way (for now).
Abandoned - Photos by Uryevich.
Ghost Towns in Japan
Flickr: Urbex Malaysia
Flickr: Benelux Urban Exploring - Belgium, Netherlands, Luxembourg.
Flickr: Urban Explorers (Nederlands)
Flickr: L'Abbandono - Italy.