Simon Cornwell's UK Urban Exploration Site. This one is exhaustive and fascinating. Next time I'm in the UK I'll see if I can get ahold of him and if he's planning any new expeditions I'll try and get on board. I'd love to get a look at some of these places, even if it's just one or two of the more "tame" sites. There's a few sites locally here, but there's nothing within driving distance on the sheer scale of most of the abandoned asylums and bases he's got documented.