The district was established by the National Assembly of Quebec on July 10, 1963 after an amendment to the Historic Sites and Monuments Act. The act made the area in the historic area of the city a "Declared Historic District" () by the province of Quebec, and was expanded the next year to an area of . It includes 1,400 buildings within the neighbourhood of La Cité, including the promontory of Cap Diamant and a strip of land below the cliffs, between the Saint-Charles River and the Saint Lawrence River. The protected perimeter of the area was delimited in two stages. The initial layout included the fortified area as well as its periphery. The second and final layout added other surrounding areas to the plan on May 6, 1964. The whole district covers a total area of 1.4 km.