The Co-Cathedral of the Assumption of Mary was built in 1169 as a Romanesque basilica of a single nave on the foundations of a pagan temple of the fourth and fifth centuries, whose remains are still visible at the back of the sanctuary at about 1.5 meters deep. The façade and the south side of the cathedral, in the middle of the eighteenth century was decorated with Romanesque arches and brick niches. In the same period the church was expanded with the addition of two side aisles, altars and other works of art. During World War II the cathedral was severely damaged. The current appearance of the building is the result of the restoration executed between 1949 and 1950.
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.