So I was recently looking around bellows falls in google maps (as you do) and stumbled on the tunnel. At first I thought it was just abandoned trackage but found the linked street view image. I think its my favorite thing I've found in a long time. that fact that a building was basically built on top of the portal and the tight clearance's all round, it just screams "mountain branch line" and I love it.
https://www.google.com/maps/@43.133...4!1s9VOkfjNeVbM9h1uzeWEeFA!2e0!7i13312!8i6656
https://en.wikipedia.org/wiki/Bellows_Falls_Tunnel
https://www.google.com/maps/@43.133...4!1s9VOkfjNeVbM9h1uzeWEeFA!2e0!7i13312!8i6656
https://en.wikipedia.org/wiki/Bellows_Falls_Tunnel