In 1955 the neighborhood was made the Historic Beacon Hill District. It was the first such district in Massachusetts, created to protect historic sites and manage urban renewal. Supporting these objectives are the non-profit Beacon Hill Civic Association and the city's Boston Preservation Alliance organizations. According to the Massachusetts Historical Commission, the historic districts "appear to have stabilized architectural fabric" of Beacon Hill.
Beacon Hill was designated a National Historic Landmark on December 19, 1962. http://en.wikipedia.org/wiki/Beacon_Hill,_Boston