Fort McKinley, Great Diamond Island

Fort McKinley is a former United States Army coastal defense fort on Great Diamond Island, Maine in Casco Bay, which operated from 1873 to 1947. It was named for President William McKinley. It included a sub-post, Fort Lyon, on Cow Island, just north of Great Diamond Island. Fort Lyon was named for Nathaniel Lyon. Both forts were part of the Coast Defenses of Portland, renamed the Harbor Defenses of Portland in 1925, a command which protected Portland's port and naval anchorage 1895-1950. In 1946 Fort Lyon was closed and turned over to the City of Portland. After Fort McKinley's closure it was transferred to the United States Navy, which sold the site to private interests in 1961. The Fort McKinley Historic District was listed on the National Register of Historic Places in 1985. ()