Independence National Historical Park is a federally protected historic district in Philadelphia, Pennsylvania that preserves several sites associated with the American Revolution and the nation's founding history. Administered by the National Park Service, the 55-acre park comprises many of Philadelphia's most-visited historic sites within the Old City a…Independence National Historical Park is a federally protected historic district in Philadelphia, Pennsylvania that preserves several sites associated with the American Revolution and the nation's founding history. Administered by the National Park Service, the 55-acre park comprises many of Philadelphia's most-visited historic sites within the Old City and Society Hill neighborhoods. The park has been nicknamed "America's most historic square mile" because of its abundance of historic landmarks.