Mysterious (or not so much) manmade(?) cave in Upton - Attributed to various groups but still unsolved, the Upton Chamber is one of hundreds of structures throughout the region with an unknown past. Photos and contact: https://www.instagram.com/lostmassachusetts/

Sources, links, blog, etc.:https://lostmassachusetts.com/a-lost-place/f/upton-chamber-e20