Old abandoned buildings are interesting to explore a lot of the time.
Been in plenty. One time even found a hoard of cigarette cards, those aren't made anymore, complete set bar 1. Weirdest thing, in the same place, was that there was a stash of old ass videogame floppy disks, found of all places, under the floorboards. IMO if I can get the last one of those cards from somewhere the full set would be worth a fair bit to a collector, and old ones too, all vintage car designs.
Same place had lead piping leading to a copper boiler. Needless to say it took a while, but eventually the pipes, etc. made an exit, leaving me the richer for it.
And the old floppy disk games were good ones too, the original system shock, terminator-future shock and others.
Another place...weird. Looked like it had been abandoned in a real hurry. Fire damage to the lower floors, once in there, found out I was not the first, somebody had left a chunk of hash behind and some valium. Won't even go into the rest of it too much, there was creepy shit going on in there. Ever heard a 13 year old female suddenly start talking in the voice of an old male? that shouldn't even be physically possible, the vocal cords are too different, for a young girl to start speaking in a gravelly old man's voice. And then get tossed through the air...glad that place got knocked down.