Image credit and copyright.
Opacity.us is an urban exploration site set up in 2002 by Brooklyn based graphic designer Tom Kirsch. It covers a wide range of buildings from abandoned hospitals to hotels through to abandoned prisons.
The site contains some of the best urban exploration photographs to be found on the net, and unlike other exploration sites, it offers the chance to download wallpapers and screen savers of selected photographs.
The site also has some depth to it, offering potted histories of the sites photographed, although the names of the more dangerous or precarious sites are changed to protect their identities.
Opacity also collects news and events that are associated with the selected abandonment's, a feature which helps to show a more rounded interest in these abandoned sites than some of the more extreme exploration sites.
Opacity also contains an active forum, which discusses the abandoned buildings featured in the site gallery, as well as news and features related to the abandonment's that have been posted to the site.