I had to see it for myself.
Because he shares my interest in all things strange and historic, my pal Jeff Stewart (founder of Paranormal Investigators of New England) joined me to see if we could rediscover the thing.
Finding it was easy; Susan had provided excellent directions. Figuring out what it was proved to be the hard part.
It clearly was not one of

It was in plain sight -- out in the open -- but we approached it with caution.
Peering through the opening we could tell that it extended a good long way under the hill that supports the railroad tracks.

Before entering, we guessed it must have been used for storage – rails maybe -- but it occurred to both of us that there would have been lots of less labor intensive ways to set up a storage shed.
Well, we’ll figure it out…
As we entered, the mystery deepened.
Shining our light toward the end of the tunnel, we discovered that there was a thick gray blanket hanging across the interior, creating sort of an optical illusion that the tunnel ended before it really did – a sort of false bottom.
This put us on guard, fearing we might not be alone.
Jeff called, “Hello” several times before we continued into the tunnel. When we moved the curtain aside it became immediately clear that someone was -- or had been – living here. His protection against intruders was just inside the curtain: a big knife.
We remained on guard until we were sure we were alone.Then we poked around a bit and found candles, pots, bedding, and books. I could imagine the vanished occupant in this lightless, damp dungeon huddled under a blanket reading mysteries by candlelight.
Not the most hospitable of homes. The place was muddy and wet. Jeff and I agreed that no one could be living there as of our visit on April 23rd. In fact nothing was living there but gigantic spiders.

Whoever had made his or her home here was a puzzle, but the real mystery was the place itself. Just exactly what was it?
The investigation continues next time. . .