That 2nd bridge you see at the Keystone Arch Bridges Trail…was once a stone arch like the others, taking a closer look the right side abutment is still stone blocks however this bridge is now primarily newer construction. Take a left after the gate onto the Pontoosuc Turnpike (also see the turnpike road bed wall of rocks)and see two cellar holes on your left, a short trail takes you to the river bank. This is Keystone Arch #2. #hikethehilltowns with the #westernmasshilltownhikers on Instagram TikTok Pinterest Flickr Twitter and Meetup