when was fort jefferson built
Fort Jefferson (1) (1846-1874) - Construction of this Third System fort began in 1846 supervised by the U.S. Army Corps of Engineers and continued for 30 years and was never completed.Named after President Thomas Jefferson.Located 70 miles west of Key West on Garden Key, Dry Tortugas Islands, Monroe County, Florida.esigned as the largest Third System brick and masonry fort in the U.S. Fort Jefferson was to be a three-tiered six-sided 420 heavy gun fort, with two sides measuring 325 feet, four sides measuring 477 feet and bastions at each corner. Some 16 millon bricks were used in its actual construction.