ShotHotspot has mapped 14 abandoned places in Penobscot, Maine, ranked by how often they're photographed, viewed and voted for. The most popular are Abandoned Dam Maine Penstock, Exploration Urbex Abandoned Umaine and Abandoned Maine Brick Exploration. Some are private property or unsafe, so get permission before you visit.
We don't know whether you're allowed to visit any of these places. Many are private property, closed to the public or unsafe: get permission from the owner or the relevant authority, and take safety precautions.