Fort Mifflin, Mud Island, Marine & Penrose Ferry Roads, Philadelphia, Philadelphia County, PA

Significance: Served as the primary fortification for the Americans in their blockade of British-occupied Philadelphia in 1777. Nearly destroyed in the British siege, Fort Mifflin was rebuilt as the first fortification undertaken by the United States. After the construction of Fort Delaware in 1820, Fort Mifflin was relegated to secondary states, but survives as a fine example of colonial stone masonry construction, as well as early 19th-century military architecture.
Unprocessed Field note material exists for this structure: FN-125, FN-126, FN-127
Survey number: HABS PA-1225
Building/structure dates: 1775 Initial Construction
Building/structure dates: 1777 Demolished
Building/structure dates: 1794 Subsequent Work
National Register of Historic Places NRIS Number: 70000554