Christiansborg Palace or Christiansborg Castle (Danish: Christiansborg Slot), on the islet of Slotsholmen in central Copenhagen, is the seat of the Danish Parliament (Folketinget), the Prime Minister's Office and the Supreme Court. Also, several parts of the palace are used by the monarchy, including the Royal Reception Rooms, the Palace Chapel and the Royal Stables.
The palace is thus the house of Denmark's three supreme powers: the executive power, the legislative power, and the judicial power. It is the only building in the world that houses all three of a country's branches of government. Christiansborg Palace is owned by the Danish state, and is run by the Palaces and Properties Agency.
The present building, the third to be built on the site, is the last in a series of successive castles and palaces constructed on the same site since the erection of the first castle in 1167. Since the early fifteenth century, the various buildings have served as the base of the central administration; until 1794 as the principal residence of the Danish kings and after 1849 as the seat of parliament.
The palace today bears witness to three eras of Danish architecture, as the result of two serious fires. The first fire occurred in 1794 and the second in 1884. The main part of the current palace, finished in 1928, is in the historicist Neo-baroque style. The chapel dates to 1826 and is in a neoclassical style. The showgrounds were built 1738-46, in a baroque style. [Wikipedia]