The structure was begun in 1858, a year after Congress authorized funds, on Hog Island in Portland Harbor.
By the end of the Civil War it was outdated with the invention of the rifle cannon that could destroy its granite structure.
Fort Gorges is listed on the National Register of Historic Places. Currently owned by the City of Portland and uninhabited, it has no ferry service.
The following is from a brief history of the fort from the “Art & History” section of the U.S. Senate internet site:
Following the War of 1812, the Army Corps of Engineers proposed that a fort be built on Hog Island Ledge, in Casco Bay at the entrance to the harbor at Portland.
Named for the colonial proprietor of Maine, Sir Fernando Gorges, it was constructed to support existing forts, including Fort Scammel built on nearby House Island in 1808.
Congress, however, did not fund construction of Fort Gorges until 1857. The walls of the fort were begun the next year, and when the Civil War broke out in 1861, work quickly advanced. It was completed in 1865 as the war ended, a granite reminder of what might have been. A modernization plan was begun in 1869, but funding was cut off in 1876, with the third level of the fort still unfinished.
“Fort Scammel and Fort Gorges, Maine.” http://www.senate.gov/artandhistory/art/artifact/Painting_33_00015.htm (accessed November 28, 2011)
McKinnon, Donna Lee. Portland Defended: A History of the United States Government Fortifications of Casco Bay, 1794-1945. 1987. (Thesis (M.A.) in History–University of Maine, 1987) [University of Maine, Raymond H. Fogler Library, Special Collections]