Christiansborg Palace is the seat of the Danish Parliament, the Danish Prime Minister's Office and the Danish 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. The first castle on the site was Absalon's Castle. According to the Danish chronicler Saxo Grammaticus, Bishop Absalon of Roskilde built a castle in 1167 on a small island outside Copenhagen Harbour. 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.
References:Rosenborg Palace was built in the period 1606-34 as Christian IV’s summerhouse just outside the ramparts of Copenhagen. Christian IV was very fond of the palace and often stayed at the castle when he resided in Copenhagen, and it was here that he died in 1648. After his death, the palace passed to his son King Frederik III, who together with his queen, Sophie Amalie, carried out several types of modernisation.
The last king who used the place as a residence was Frederik IV, and around 1720, Rosenborg was abandoned in favor of Frederiksborg Palace.Through the 1700s, considerable art treasures were collected at Rosenborg Castle, among other things items from the estates of deceased royalty and from Christiansborg after the fire there in 1794.
Soon the idea of a museum arose, and that was realised in 1833, which is The Royal Danish Collection’s official year of establishment.