The area of Christiania consists of the former military barracks of Bådsmandsstræde and parts of the city ramparts. The ramparts and the borough of Christianshavn (then a separate city) were established in 1617 by King Christian IV by reclaiming the low beaches and islets between Copenhagen and Amager. After the siege of Copenhagen during the harsh wars with Sweden, the ramparts were reinforced during 1682 to 1692 under Christian V to form a complete defence ring. The western ramparts of Copenhagen were demolished during the 19th century, but those of Christianshavn were allowed to remain. They are today considered among the finest surviving 17th century defence works in the world.
The barracks of Bådsmandsstræde (Bådsmandsstrædes Kaserne) housed the Royal Artillery Regiment, the Army Materiel Command and ammunition laboratories and depots. Less used after World War II, the barracks were abandoned during 1967 to 1971.
The adjacent area to the north, Holmen, was Denmark's main naval base until the 1990s. It is an area in development, home to the new Copenhagen Opera House (not to be confused with the first and still existing venue called "Operaen", a concert venue in Christiania) and schools. An area further north is still used by the navy, but open to the public during daytime.
The outermost defence line, Enveloppen, has been renamed Dyssen in Christiania language (except for the southernmost tip of it which was not annexed by Christiania). It is connected to central Christiania by a bridge across the main moat or can be reached by the path beginning at Christmas Møllers Plads. Four gunpowder storehouses line the redans. They were built 1779-80 to replace a storage in central Copenhagen, at Østerport, which blasted infamously in 1770, killing 50 people. The buildings are renamed Aircondition, Autogena, Fakirskolen (The Fakir School) and Kosmiske Blomst(Cosmic Flower) and have, although protected, been
