Secret in the woods

We were strolling through the woods near the local restaurant "Schillerstein", when we suddenly detected something "artificial": an old, deserted lodge. Even more gripping: nearby we found the entrance to that old tunnel. Later, the aged owner of the tavern told us, that this tunnel once was used to transport abort from a stone quarry, that was abandondend around the year 1900. Fascinating!
Maybe we should check, whether the tunnel today is already used for geocaching?!