I used to work in a school that was based in a building which was ~150yr old. One day there was a break in the network. did the usual stuff and ruled out everything else so had to inspect the cable.
The cable went into the foundations so I had to go down with a torch and trace it. About 10m in the cable passed under a boulder that had been left from construction. the boulder must have weighed a good few tons and had moved on level ground to roll over and nip the cable. Spooky.
The only thing we could think of is that we were in a known UK earthquake area. It might have been a tremor which wasn't noticeable to us but which was enough to tip over the rock.
I also found love poetry from the 1800s in a pigeon shit filled loft and incredibly racist comics from the 1920s in a coom.