I’ve been looking for the history of this: a monolithic, ruinous stonework running alongside the horse trail through Chesterfield Gorge. USGS topographical maps surveyed in 1886 (see here, try the SW quadrant) shows an unpaved road following most of the length of the Westfield River, with even a couple of houses scattered along it. None of which are there now. Google Earth barely shows the road. So who knows what this thing is. It’s not a mill foundation, unless the river has been dammed and rerouted and the mill abandoned long enough to rot away utterly, leaving not even loam. Stranger things have happened, of course. It’s not the remains of a bridge either, because there’s no matching stonework on the far side. The best I can judge, this little linteled passageway was constructed purely for its future aesthetics as an overgrown ruin. Of course if I really cared, I could go digging through deeds at the hall of records and find the real answer. Note that I do not.