View of historic Fort Gorges in the busy harbor on Casco Bay in Portland, Maine's largest city. Built from 1858 to 1864, just before and during the U.S. Civil War, it saw no battles, and no troops were ever stationed there. Advancing military technology, including ironclad ships and long-range guns, made the fort obsolete before it could be used. The fort is now a park, accessible only by boat. Photo by Carol Highsmith, 2017.