On my way down from Pwll-y-Wrach, in the distance, I spotted something that on the map was only marked as "hospital". Apparently I stumbled upon Talgarth Asylum, a clinic that was closed only 20 years ago. In that 20 years, it got stripped of the slate on the roof and left to rot. The locals use the field next to it for picnic, among a serious amount of asbestos warning signs - by looking in the windows there's cracked AIB ceiling everywhere, so I got as far as I could fast.
The internet then showed me how this place looked only 11 years ago1 and it's hard to believe how much destruction 11 years of weather - and looting - can do to a place.
(Oh, by the way: this entry was written by Peter Molnar, and originally posted on petermolnar dot net.)