Lisbon District
Lisbon District (, ) is a district located in the South Central Portugal, the district capital is the city of Lisbon, also the national capital. From its creation until 1926, it included the area of the current Setúbal District.
National redoubt
Since the early 19th century to the World War II, Lisbon was considered the national redoubt of Portugal. Besides being the capital, the largest city and the major port of the country, Lisbon was considered the last defensible redoubt in case of an invasion of Portugal by a major power. During this period, successive systems of defense were implemented.